diff --git a/README.md b/README.md
index 6ed500b..e196333 100644
--- a/README.md
+++ b/README.md
@@ -35,11 +35,21 @@ following servers:
    that all incoming SMP messages for the creditors stored on the
    PostgreSQL server instance, are routed to this queue.
 
-   Also, a [RabbitMQ exchange] named **`creditors_out`** must be configured
-   on the broker instance. This exchange is for messages that must be sent
-   to accounting authorities. The routing key will represent the debtor ID
-   as hexadecimal (lowercase). For example, for debtor ID equal to 10, the
-   routing key will be "00.00.00.00.00.00.00.0a".
+   Also, the following [RabbitMQ exchanges] must be configured on the
+   broker instance:
+
+   - **`creditors_out`**: For messages that must be sent to accounting
+     authorities. The routing key will represent the debtor ID as
+     hexadecimal (lowercase). For example, for debtor ID equal to 10, the
+     routing key will be "00.00.00.00.00.00.00.0a".
+
+   - **`to_trade`**: For policy change notifications that must be sent to
+     the subsystem that is responsible for performing automatic circular
+     trades. The routing key will represent the highest 24 bits of the MD5
+     digest of the creditor ID. For example, if the creditor ID is 123, the
+     routing key will be "1.1.1.1.1.1.0.0.0.0.0.1.0.0.0.0.0.1.1.0.0.0.1.1".
+     This allows different creditor accounts to be handled by different
+     database servers (sharding).
 
    **Note:** If you execute the "configure" command (see below), with
    the environment variable `SETUP_RABBITMQ_BINDINGS` set to `yes`, an
@@ -146,7 +156,7 @@ PROTOCOL_BROKER_THREADS=3
 PROTOCOL_BROKER_PREFETCH_COUNT=10
 
 # The binding key with which the "$PROTOCOL_BROKER_QUEUE"
-# RabbitMQ queue is bound to the "creditors_in" RabbitMQ topic
+# RabbitMQ queue is bound to the incoming messages' topic
 # exchange (default "#"). The binding key must consist of zero or
 # more 0s or 1s, separated by dots, ending with a hash symbol.
 # For example: "0.1.#", "1.#", or "#".
@@ -230,7 +240,8 @@ container allows you to execute the following *documented commands*:
   RabbitMQ broker, and remove the messages from the PostgreSQL database.
 
 * `flush_configure_accounts`, `flush_prepare_transfers`,
-  `flush_finalize_transfers`
+  `flush_finalize_transfers`, `flush_updated_ledgers`,
+  `flush_updated_policies`, `flush_updated_flags`
 
   Starts additional worker processes that send particular type of outgoing
   messages to the RabbitMQ broker, and remove the messages from the
@@ -328,7 +339,7 @@ can be used for end-to-end testing.
 [Swaptacular Messaging Protocol]: https://github.com/swaptacular/swpt_accounts/blob/master/protocol.rst
 [RabbitMQ]: https://www.rabbitmq.com/
 [RabbitMQ queue]: https://www.cloudamqp.com/blog/part1-rabbitmq-for-beginners-what-is-rabbitmq.html
-[RabbitMQ exchange]: https://www.cloudamqp.com/blog/part4-rabbitmq-for-beginners-exchanges-routing-keys-bindings.html
+[RabbitMQ exchanges]: https://www.cloudamqp.com/blog/part4-rabbitmq-for-beginners-exchanges-routing-keys-bindings.html
 [Redis]: https://redis.io/
 [OAuth 2.0]: https://oauth.net/2/
 [nginx]: https://en.wikipedia.org/wiki/Nginx
diff --git a/development.env b/development.env
index cc2fa45..4845f9e 100644
--- a/development.env
+++ b/development.env
@@ -2,7 +2,7 @@
 # Configuration settings #
 ##########################
 
-MIN_CREDITOR_ID=0x0000010000000000
+MIN_CREDITOR_ID=0x0000010100000000
 MAX_CREDITOR_ID=0x000001ffffffffff
 
 PIN_PROTECTION_SECRET=
@@ -51,6 +51,9 @@ APP_PROCESS_LEDGER_UPDATES_MAX_COUNT=100000
 APP_FLUSH_CONFIGURE_ACCOUNTS_BURST_COUNT=10000
 APP_FLUSH_PREPARE_TRANSFERS_BURST_COUNT=10000
 APP_FLUSH_FINALIZE_TRANSFERS_BURST_COUNT=10000
+APP_FLUSH_UPDATED_LEDGER_BURST_COUNT=10000
+APP_FLUSH_UPDATED_POLICY_BURST_COUNT=10000
+APP_FLUSH_UPDATED_FLAGS_BURST_COUNT=10000
 APP_CREDITORS_SCAN_DAYS=7
 APP_CREDITORS_SCAN_BLOCKS_PER_QUERY=40
 APP_CREDITORS_SCAN_BEAT_MILLISECS=25
diff --git a/docker/entrypoint.sh b/docker/entrypoint.sh
index 6301e7a..563d422 100755
--- a/docker/entrypoint.sh
+++ b/docker/entrypoint.sh
@@ -115,11 +115,15 @@ case $1 in
         exec flask swpt_creditors "$@"
         ;;
     flush_configure_accounts | flush_prepare_transfers | flush_finalize_transfers \
+        | flush_updated_ledgers | flush_updated_policies | flush_updated_flags \
         | flush_all)
 
         flush_configure_accounts=ConfigureAccountSignal
         flush_prepare_transfers=PrepareTransferSignal
         flush_finalize_transfers=FinalizeTransferSignal
+        flush_updated_ledgers=UpdatedLedgerSignal
+        flush_updated_policies=UpdatedPolicySignal
+        flush_updated_flags=UpdatedFlagsSignal
         flush_all=
 
         # For example: if `$1` is "flush_configure_accounts",
diff --git a/migrations/versions/4260660af5b1_.py b/migrations/versions/4260660af5b1_.py
new file mode 100644
index 0000000..9d2f94b
--- /dev/null
+++ b/migrations/versions/4260660af5b1_.py
@@ -0,0 +1,53 @@
+"""empty message
+
+Revision ID: 4260660af5b1
+Revises: 824705144577
+Create Date: 2023-10-11 16:22:24.946584
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '4260660af5b1'
+down_revision = '824705144577'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('updated_ledger_signal',
+    sa.Column('creditor_id', sa.BigInteger(), nullable=False),
+    sa.Column('debtor_id', sa.BigInteger(), nullable=False),
+    sa.Column('update_id', sa.BigInteger(), nullable=False),
+    sa.Column('creation_date', sa.DATE(), nullable=False),
+    sa.Column('account_id', sa.String(), nullable=False),
+    sa.Column('principal', sa.BigInteger(), nullable=False),
+    sa.Column('last_transfer_number', sa.BigInteger(), nullable=False),
+    sa.Column('ts', sa.TIMESTAMP(timezone=True), nullable=False),
+    sa.Column('inserted_at', sa.TIMESTAMP(timezone=True), nullable=False),
+    sa.PrimaryKeyConstraint('creditor_id', 'debtor_id', 'update_id')
+    )
+    op.create_table('updated_policy_signal',
+    sa.Column('creditor_id', sa.BigInteger(), nullable=False),
+    sa.Column('debtor_id', sa.BigInteger(), nullable=False),
+    sa.Column('update_id', sa.BigInteger(), nullable=False),
+    sa.Column('policy_name', sa.String(), nullable=True),
+    sa.Column('min_principal', sa.BigInteger(), nullable=False),
+    sa.Column('max_principal', sa.BigInteger(), nullable=False),
+    sa.Column('peg_exchange_rate', sa.FLOAT(), nullable=True),
+    sa.Column('peg_debtor_id', sa.BigInteger(), nullable=True),
+    sa.Column('ts', sa.TIMESTAMP(timezone=True), nullable=False),
+    sa.Column('inserted_at', sa.TIMESTAMP(timezone=True), nullable=False),
+    sa.PrimaryKeyConstraint('creditor_id', 'debtor_id', 'update_id')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('updated_policy_signal')
+    op.drop_table('updated_ledger_signal')
+    # ### end Alembic commands ###
diff --git a/migrations/versions/4e310d9db669_.py b/migrations/versions/4e310d9db669_.py
new file mode 100644
index 0000000..45a67e9
--- /dev/null
+++ b/migrations/versions/4e310d9db669_.py
@@ -0,0 +1,36 @@
+"""empty message
+
+Revision ID: 4e310d9db669
+Revises: 4260660af5b1
+Create Date: 2023-10-13 16:39:40.541127
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = '4e310d9db669'
+down_revision = '4260660af5b1'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.create_table('updated_flags_signal',
+    sa.Column('creditor_id', sa.BigInteger(), nullable=False),
+    sa.Column('debtor_id', sa.BigInteger(), nullable=False),
+    sa.Column('update_id', sa.BigInteger(), nullable=False),
+    sa.Column('config_flags', sa.Integer(), nullable=False),
+    sa.Column('ts', sa.TIMESTAMP(timezone=True), nullable=False),
+    sa.Column('inserted_at', sa.TIMESTAMP(timezone=True), nullable=False),
+    sa.PrimaryKeyConstraint('creditor_id', 'debtor_id', 'update_id')
+    )
+    # ### end Alembic commands ###
+
+
+def downgrade():
+    # ### commands auto generated by Alembic - please adjust! ###
+    op.drop_table('updated_flags_signal')
+    # ### end Alembic commands ###
diff --git a/swpt_creditors/__init__.py b/swpt_creditors/__init__.py
index bf731b0..0c4807a 100644
--- a/swpt_creditors/__init__.py
+++ b/swpt_creditors/__init__.py
@@ -227,6 +227,9 @@ class Configuration(metaclass=MetaEnvReader):
     APP_FLUSH_CONFIGURE_ACCOUNTS_BURST_COUNT = 10000
     APP_FLUSH_PREPARE_TRANSFERS_BURST_COUNT = 10000
     APP_FLUSH_FINALIZE_TRANSFERS_BURST_COUNT = 10000
+    APP_FLUSH_UPDATED_LEDGER_BURST_COUNT = 10000
+    APP_FLUSH_UPDATED_POLICY_BURST_COUNT = 10000
+    APP_FLUSH_UPDATED_FLAGS_BURST_COUNT = 10000
     APP_CREDITORS_SCAN_DAYS = 7.0
     APP_CREDITORS_SCAN_BLOCKS_PER_QUERY = 40
     APP_CREDITORS_SCAN_BEAT_MILLISECS = 25
diff --git a/swpt_creditors/actors.py b/swpt_creditors/actors.py
index 2bd54b6..bb6f58c 100644
--- a/swpt_creditors/actors.py
+++ b/swpt_creditors/actors.py
@@ -160,8 +160,9 @@ def _on_rejected_direct_transfer_signal(
     **kwargs
 ) -> None:
     if coordinator_type != CT_DIRECT:  # pragma: no cover
-        _LOGGER.error('Unexpected coordinator type: "%s"', coordinator_type)
-        return
+        raise RuntimeError(
+            f'Unexpected coordinator type: "{coordinator_type}"'
+        )
 
     procedures.process_rejected_direct_transfer_signal(
         coordinator_id=coordinator_id,
@@ -190,8 +191,9 @@ def _on_prepared_direct_transfer_signal(
     **kwargs
 ) -> None:
     if coordinator_type != CT_DIRECT:  # pragma: no cover
-        _LOGGER.error('Unexpected coordinator type: "%s"', coordinator_type)
-        return
+        raise RuntimeError(
+            f'Unexpected coordinator type: "{coordinator_type}"'
+        )
 
     procedures.process_prepared_direct_transfer_signal(
         debtor_id=debtor_id,
@@ -220,8 +222,9 @@ def _on_finalized_direct_transfer_signal(
     **kwargs
 ) -> None:
     if coordinator_type != CT_DIRECT:  # pragma: no cover
-        _LOGGER.error('Unexpected coordinator type: "%s"', coordinator_type)
-        return
+        raise RuntimeError(
+            f'Unexpected coordinator type: "{coordinator_type}"'
+        )
 
     procedures.process_finalized_direct_transfer_signal(
         debtor_id=debtor_id,
diff --git a/swpt_creditors/cli.py b/swpt_creditors/cli.py
index 8b180c6..31eda92 100644
--- a/swpt_creditors/cli.py
+++ b/swpt_creditors/cli.py
@@ -47,8 +47,13 @@ def subscribe():  # pragma: no cover
 
     """
 
-    from .extensions import CREDITORS_IN_EXCHANGE, CREDITORS_OUT_EXCHANGE
+    from .extensions import (
+        CREDITORS_IN_EXCHANGE,
+        CREDITORS_OUT_EXCHANGE,
+        TO_TRADE_EXCHANGE,
+    )
 
+    CA_CREDITORS_EXCHANGE = "ca.creditors"
     logger = logging.getLogger(__name__)
     queue_name = current_app.config["PROTOCOL_BROKER_QUEUE"]
     routing_key = current_app.config["PROTOCOL_BROKER_QUEUE_ROUTING_KEY"]
@@ -59,11 +64,32 @@ def subscribe():  # pragma: no cover
 
     # declare exchanges
     channel.exchange_declare(
-        CREDITORS_IN_EXCHANGE, exchange_type="topic", durable=True
+        CREDITORS_IN_EXCHANGE, exchange_type="headers", durable=True
+    )
+    channel.exchange_declare(
+        CA_CREDITORS_EXCHANGE, exchange_type="topic", durable=True
     )
     channel.exchange_declare(
         CREDITORS_OUT_EXCHANGE, exchange_type="topic", durable=True
     )
+    channel.exchange_declare(
+        TO_TRADE_EXCHANGE, exchange_type="topic", durable=True
+    )
+
+    # declare exchange bindings
+    channel.exchange_bind(
+        source=CREDITORS_IN_EXCHANGE,
+        destination=CA_CREDITORS_EXCHANGE,
+        arguments={
+            "x-match": "all",
+            "ca-creditors": True,
+        },
+    )
+    logger.info(
+        'Created a binding from "%s" to the "%s" exchange.',
+        CREDITORS_IN_EXCHANGE,
+        CA_CREDITORS_EXCHANGE,
+    )
 
     # declare a corresponding dead-letter queue
     channel.queue_declare(dead_letter_queue_name, durable=True)
@@ -82,13 +108,13 @@ def subscribe():  # pragma: no cover
 
     # bind the queue
     channel.queue_bind(
-        exchange=CREDITORS_IN_EXCHANGE,
+        exchange=CA_CREDITORS_EXCHANGE,
         queue=queue_name,
         routing_key=routing_key,
     )
     logger.info(
         'Created a binding from "%s" to "%s" with routing key "%s".',
-        CREDITORS_IN_EXCHANGE,
+        CA_CREDITORS_EXCHANGE,
         queue_name,
         routing_key,
     )
diff --git a/swpt_creditors/extensions.py b/swpt_creditors/extensions.py
index dcbca07..55595db 100644
--- a/swpt_creditors/extensions.py
+++ b/swpt_creditors/extensions.py
@@ -19,6 +19,7 @@
 CREDITORS_IN_EXCHANGE = "creditors_in"
 DEBTORS_OUT_EXCHANGE = "debtors_out"
 DEBTORS_IN_EXCHANGE = "debtors_in"
+TO_TRADE_EXCHANGE = "to_trade"
 
 
 warnings.filterwarnings(
diff --git a/swpt_creditors/models/signals.py b/swpt_creditors/models/signals.py
index 13505c5..f29e505 100644
--- a/swpt_creditors/models/signals.py
+++ b/swpt_creditors/models/signals.py
@@ -1,8 +1,12 @@
 from __future__ import annotations
 from flask import current_app
 from marshmallow import Schema, fields
-from swpt_pythonlib.utils import i64_to_hex_routing_key
-from swpt_creditors.extensions import db, CREDITORS_OUT_EXCHANGE
+from swpt_pythonlib.utils import i64_to_hex_routing_key, calc_bin_routing_key
+from swpt_creditors.extensions import (
+    db,
+    CREDITORS_OUT_EXCHANGE,
+    TO_TRADE_EXCHANGE,
+)
 from .common import Signal, CT_DIRECT
 
 
@@ -123,3 +127,122 @@ def routing_key(self):  # pragma: no cover
     @classproperty
     def signalbus_burst_count(self):
         return current_app.config["APP_FLUSH_FINALIZE_TRANSFERS_BURST_COUNT"]
+
+
+class UpdatedLedgerSignal(Signal):
+    """Notifies about a change in account's principal balance.
+
+    In addition to the new principal balance, the notification contains the
+    account's identity (a string), the account's creation date, and the ID
+    (a number) of latest transfer to/from the account. The subsystem that
+    performs automatic circular trades needs this information to do its
+    work.
+    """
+
+    exchange_name = TO_TRADE_EXCHANGE
+
+    class __marshmallow__(Schema):
+        type = fields.Constant("UpdatedLedger")
+        debtor_id = fields.Integer()
+        creditor_id = fields.Integer()
+        update_id = fields.Integer()
+        account_id = fields.String()
+        creation_date = fields.Date()
+        principal = fields.Integer()
+        last_transfer_number = fields.Integer()
+        ts = fields.DateTime()
+
+    __marshmallow_schema__ = __marshmallow__()
+
+    creditor_id = db.Column(db.BigInteger, primary_key=True)
+    debtor_id = db.Column(db.BigInteger, primary_key=True)
+    update_id = db.Column(db.BigInteger, primary_key=True)
+    creation_date = db.Column(db.DATE, nullable=False)
+    account_id = db.Column(db.String, nullable=False)
+    principal = db.Column(db.BigInteger, nullable=False)
+    last_transfer_number = db.Column(db.BigInteger, nullable=False)
+    ts = db.Column(db.TIMESTAMP(timezone=True), nullable=False)
+
+    @property
+    def routing_key(self):  # pragma: no cover
+        return calc_bin_routing_key(self.creditor_id)
+
+    @classproperty
+    def signalbus_burst_count(self):
+        return current_app.config["APP_FLUSH_UPDATED_LEDGER_BURST_COUNT"]
+
+
+class UpdatedPolicySignal(Signal):
+    """Notifies about a change in account's automatic exchange policy.
+
+    The subsystem that performs automatic circular trades needs this
+    information to do its work.
+    """
+
+    exchange_name = TO_TRADE_EXCHANGE
+
+    class __marshmallow__(Schema):
+        type = fields.Constant("UpdatedPolicy")
+        debtor_id = fields.Integer()
+        creditor_id = fields.Integer()
+        update_id = fields.Integer()
+        policy_name = fields.String()
+        min_principal = fields.Integer()
+        max_principal = fields.Integer()
+        peg_exchange_rate = fields.Float()
+        peg_debtor_id = fields.Integer()
+        ts = fields.DateTime()
+
+    __marshmallow_schema__ = __marshmallow__()
+
+    creditor_id = db.Column(db.BigInteger, primary_key=True)
+    debtor_id = db.Column(db.BigInteger, primary_key=True)
+    update_id = db.Column(db.BigInteger, primary_key=True)
+    policy_name = db.Column(db.String)
+    min_principal = db.Column(db.BigInteger, nullable=False)
+    max_principal = db.Column(db.BigInteger, nullable=False)
+    peg_exchange_rate = db.Column(db.FLOAT)
+    peg_debtor_id = db.Column(db.BigInteger)
+    ts = db.Column(db.TIMESTAMP(timezone=True), nullable=False)
+
+    @property
+    def routing_key(self):  # pragma: no cover
+        return calc_bin_routing_key(self.creditor_id)
+
+    @classproperty
+    def signalbus_burst_count(self):
+        return current_app.config["APP_FLUSH_UPDATED_POLICY_BURST_COUNT"]
+
+
+class UpdatedFlagsSignal(Signal):
+    """Notifies about a change in account's configuration flags.
+
+    The subsystem that performs automatic circular trades needs this
+    information to do its work.
+    """
+
+    exchange_name = TO_TRADE_EXCHANGE
+
+    class __marshmallow__(Schema):
+        type = fields.Constant("UpdatedFlags")
+        debtor_id = fields.Integer()
+        creditor_id = fields.Integer()
+        update_id = fields.Integer()
+        config_flags = fields.Integer()
+        ts = fields.DateTime()
+
+    __marshmallow_schema__ = __marshmallow__()
+
+    creditor_id = db.Column(db.BigInteger, primary_key=True)
+    debtor_id = db.Column(db.BigInteger, primary_key=True)
+    update_id = db.Column(db.BigInteger, primary_key=True)
+    config_flags = db.Column(db.Integer, nullable=False)
+    ts = db.Column(db.TIMESTAMP(timezone=True), nullable=False)
+
+    @property
+    def routing_key(self):  # pragma: no cover
+        return calc_bin_routing_key(self.creditor_id)
+
+    @classproperty
+    def signalbus_burst_count(self):
+        return current_app.config["APP_FLUSH_UPDATED_FLAGS_BURST_COUNT"]
diff --git a/swpt_creditors/procedures/account_updates.py b/swpt_creditors/procedures/account_updates.py
index 3c3401b..814e935 100644
--- a/swpt_creditors/procedures/account_updates.py
+++ b/swpt_creditors/procedures/account_updates.py
@@ -7,6 +7,7 @@
 from swpt_creditors.models import (
     AccountData,
     ConfigureAccountSignal,
+    UpdatedLedgerSignal,
     LogEntry,
     PendingLogEntry,
     PendingLedgerUpdate,
@@ -130,6 +131,7 @@ def process_account_update_signal(
 
     assert creation_date >= data.creation_date
     is_new_server_account = creation_date > data.creation_date
+    is_account_id_changed = account_id != data.account_id
     is_config_effectual = (
         last_config_ts == data.last_config_ts
         and last_config_seqnum == data.last_config_seqnum
@@ -172,19 +174,44 @@ def process_account_update_signal(
     if is_info_updated:
         _insert_info_update_pending_log_entry(data, current_ts)
 
-    if is_new_server_account:
+    if is_new_server_account or is_account_id_changed:
+        if is_new_server_account:
+            data.ledger_pending_transfer_ts = None
+            ledger_principal = 0
+            ledger_last_transfer_number = 0
+        else:  # pragma: no cover
+            # When the `account_id` field is changed, we should send a
+            # corresponding `UpdatedLedgerSignal` message. To do this
+            # consistently with the Web API, first we need to add a ledger
+            # update log entry, even when the ledger did not really change.
+            assert is_account_id_changed
+            ledger_principal = data.ledger_principal
+            ledger_last_transfer_number = data.ledger_last_transfer_number
+
         log_entry = _update_ledger(
             data=data,
-            transfer_number=0,
+            transfer_number=ledger_last_transfer_number,
             acquired_amount=0,
-            principal=0,
+            principal=ledger_principal,
             current_ts=current_ts,
+            always_insert_ledger_update_log_entry=True,
         )
         if log_entry:
+            db.session.add(
+                UpdatedLedgerSignal(
+                    creditor_id=creditor_id,
+                    debtor_id=debtor_id,
+                    update_id=data.ledger_latest_update_id,
+                    account_id=data.account_id,
+                    creation_date=data.creation_date,
+                    principal=ledger_principal,
+                    last_transfer_number=ledger_last_transfer_number,
+                    ts=current_ts,
+                )
+            )
             db.session.add(log_entry)
             db.session.scalar(uid_seq)
 
-        data.ledger_pending_transfer_ts = None
         ensure_pending_ledger_update(data.creditor_id, data.debtor_id)
 
 
@@ -303,6 +330,16 @@ def process_pending_ledger_update(
         db.session.delete(pending_ledger_update)
 
     if log_entry:
+        db.session.add(UpdatedLedgerSignal(
+            creditor_id=creditor_id,
+            debtor_id=debtor_id,
+            update_id=data.ledger_latest_update_id,
+            account_id=data.account_id,
+            creation_date=data.creation_date,
+            principal=data.ledger_principal,
+            last_transfer_number=data.ledger_last_transfer_number,
+            ts=current_ts,
+        ))
         db.session.add(log_entry)
         db.session.scalar(uid_seq)
 
@@ -393,6 +430,7 @@ def _update_ledger(
     acquired_amount: int,
     principal: int,
     current_ts: datetime,
+    always_insert_ledger_update_log_entry: bool = False,
 ) -> Optional[PendingLogEntry]:
     should_insert_ledger_update_log_entry = (
         _make_correcting_ledger_entry_if_necessary(
@@ -426,7 +464,10 @@ def _update_ledger(
     data.ledger_principal = principal
     data.ledger_last_transfer_number = transfer_number
 
-    if should_insert_ledger_update_log_entry:
+    if (
+        should_insert_ledger_update_log_entry
+        or always_insert_ledger_update_log_entry
+    ):
         data.ledger_latest_update_id += 1
         data.ledger_latest_update_ts = current_ts
 
diff --git a/swpt_creditors/procedures/accounts.py b/swpt_creditors/procedures/accounts.py
index 892d5c6..e77539a 100644
--- a/swpt_creditors/procedures/accounts.py
+++ b/swpt_creditors/procedures/accounts.py
@@ -7,6 +7,9 @@
     Account,
     AccountData,
     ConfigureAccountSignal,
+    UpdatedPolicySignal,
+    UpdatedLedgerSignal,
+    UpdatedFlagsSignal,
     AccountDisplay,
     AccountKnowledge,
     AccountExchange,
@@ -15,6 +18,9 @@
     Creditor,
     DEFAULT_NEGLIGIBLE_AMOUNT,
     DEFAULT_CONFIG_FLAGS,
+    DATE0,
+    MIN_INT64,
+    MAX_INT64,
     uid_seq,
 )
 from .common import (
@@ -194,6 +200,14 @@ def update_account_config(
     data.last_config_seqnum = increment_seqnum(data.last_config_seqnum)
     data.is_config_effectual = False
 
+    db.session.add(UpdatedFlagsSignal(
+        creditor_id=creditor_id,
+        debtor_id=debtor_id,
+        update_id=latest_update_id,
+        config_flags=data.config_flags,
+        ts=current_ts,
+    ))
+
     paths, types = get_paths_and_types()
     db.session.add(
         PendingLogEntry(
@@ -407,6 +421,18 @@ def update_account_exchange(
     perform_update()
     exchange.latest_update_ts = current_ts
 
+    db.session.add(UpdatedPolicySignal(
+        creditor_id=creditor_id,
+        debtor_id=debtor_id,
+        update_id=latest_update_id,
+        policy_name=exchange.policy,
+        min_principal=exchange.min_principal,
+        max_principal=exchange.max_principal,
+        peg_exchange_rate=exchange.peg_exchange_rate,
+        peg_debtor_id=exchange.peg_debtor_id,
+        ts=current_ts,
+    ))
+
     paths, types = get_paths_and_types()
     db.session.add(
         PendingLogEntry(
@@ -579,6 +605,40 @@ def _log_account_deletion(
             is_deleted=True,
         )
 
+    # NOTE: When an account has been deleted, notification messages must be
+    # sent to the subsystem that performs automatic circular trades. These
+    # are otherwise regular notifications, but they contain the default safe
+    # values for all of the fields. (The default values forbid all automatic
+    # circular trades for the account.)
+    db.session.add(UpdatedLedgerSignal(
+        creditor_id=creditor_id,
+        debtor_id=debtor_id,
+        update_id=object_update_id,
+        account_id='',
+        creation_date=DATE0,
+        principal=0,
+        last_transfer_number=0,
+        ts=current_ts,
+    ))
+    db.session.add(UpdatedPolicySignal(
+        creditor_id=creditor_id,
+        debtor_id=debtor_id,
+        update_id=object_update_id,
+        policy_name=None,
+        min_principal=MIN_INT64,
+        max_principal=MAX_INT64,
+        peg_exchange_rate=None,
+        peg_debtor_id=None,
+        ts=current_ts,
+    ))
+    db.session.add(UpdatedFlagsSignal(
+        creditor_id=creditor_id,
+        debtor_id=debtor_id,
+        update_id=object_update_id,
+        config_flags=DEFAULT_CONFIG_FLAGS,
+        ts=current_ts,
+    ))
+
 
 def _insert_info_update_pending_log_entry(
     data: AccountData, current_ts: datetime
diff --git a/swpt_creditors/procedures/common.py b/swpt_creditors/procedures/common.py
index 0667033..c99de5d 100644
--- a/swpt_creditors/procedures/common.py
+++ b/swpt_creditors/procedures/common.py
@@ -27,6 +27,7 @@
     AccountData.creditor_id,
     AccountData.debtor_id,
     AccountData.creation_date,
+    AccountData.account_id,
     AccountData.ledger_principal,
     AccountData.ledger_last_entry_id,
     AccountData.ledger_last_transfer_number,
diff --git a/swpt_creditors/schemas/accounts.py b/swpt_creditors/schemas/accounts.py
index c10b953..73df4c4 100644
--- a/swpt_creditors/schemas/accounts.py
+++ b/swpt_creditors/schemas/accounts.py
@@ -412,10 +412,11 @@ class AccountLedgerSchema(MutableResourceSchema):
             format="int64",
             description=(
                 "The `entryID` of the next ledger entry to come. This will"
-                " always be a positive number. The first ledger entry for each"
-                " account will have an ID of `1`, and the ID of each"
-                " subsequent ledger entry will be equal to the ID of the"
-                " previous ledger entry plus one."
+                " always be a positive number. Normally, the entry ID of the"
+                " first ledger entry for each account will be `1`, but this is"
+                " not guaranteed. What is guaranteed though, is that the ID"
+                " of each subsequent ledger entry will be equal to the ID of"
+                " the previous ledger entry plus one."
             ),
             example=123,
         ),
diff --git a/swpt_creditors/table_scanners.py b/swpt_creditors/table_scanners.py
index f627d8d..9f69b45 100644
--- a/swpt_creditors/table_scanners.py
+++ b/swpt_creditors/table_scanners.py
@@ -14,6 +14,7 @@
     LedgerEntry,
     CommittedTransfer,
     PendingLedgerUpdate,
+    UpdatedLedgerSignal,
     uid_seq,
     is_valid_creditor_id,
 )
@@ -477,6 +478,17 @@ def _update_ledger(
         data.ledger_latest_update_id += 1
         data.ledger_latest_update_ts = current_ts
 
+        db.session.add(UpdatedLedgerSignal(
+            creditor_id=data.creditor_id,
+            debtor_id=data.debtor_id,
+            update_id=data.ledger_latest_update_id,
+            account_id=data.account_id,
+            creation_date=data.creation_date,
+            principal=principal,
+            last_transfer_number=data.ledger_last_transfer_number,
+            ts=current_ts,
+        ))
+
         return PendingLogEntry(
             creditor_id=creditor_id,
             added_at=current_ts,
diff --git a/tests/conftest.py b/tests/conftest.py
index 1f1dec2..095fbc9 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -61,6 +61,9 @@ def db_session(app):
         "TRUNCATE TABLE configure_account_signal",
         "TRUNCATE TABLE prepare_transfer_signal",
         "TRUNCATE TABLE finalize_transfer_signal",
+        "TRUNCATE TABLE updated_ledger_signal",
+        "TRUNCATE TABLE updated_policy_signal",
+        "TRUNCATE TABLE updated_flags_signal",
     ]:
         db.session.execute(sqlalchemy.text(cmd))
     db.session.commit()
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 63fce06..aceb4c7 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -251,6 +251,7 @@ def test_scan_accounts(app, db_session, current_ts):
     data2.principal = 1000
     data2.ledger_latest_update_ts = current_ts - timedelta(days=60)
     data2.last_config_ts = current_ts - timedelta(days=1000)
+    data2_creation_date = data2.creation_date
 
     data3 = m.AccountData.query.filter_by(debtor_id=3).one()
     data3.last_transfer_number = 1
@@ -291,6 +292,14 @@ def test_scan_accounts(app, db_session, current_ts):
     assert le.principal == 1000
     assert le.added_at >= current_ts
 
+    uls = m.UpdatedLedgerSignal.query.one()
+    assert uls.creditor_id == C_ID
+    assert uls.debtor_id == 2
+    assert uls.creation_date == data2_creation_date
+    assert uls.principal == 1000
+    assert uls.last_transfer_number == 0
+    assert isinstance(uls.ts, date)
+
     data2 = m.AccountData.query.filter_by(debtor_id=2).one()
 
     ple = m.PendingLogEntry.query.filter_by(
diff --git a/tests/test_models.py b/tests/test_models.py
index 6d78f3d..f845e85 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -8,6 +8,9 @@ def test_sibnalbus_burst_count(app):
     assert isinstance(m.ConfigureAccountSignal.signalbus_burst_count, int)
     assert isinstance(m.PrepareTransferSignal.signalbus_burst_count, int)
     assert isinstance(m.FinalizeTransferSignal.signalbus_burst_count, int)
+    assert isinstance(m.UpdatedLedgerSignal.signalbus_burst_count, int)
+    assert isinstance(m.UpdatedPolicySignal.signalbus_burst_count, int)
+    assert isinstance(m.UpdatedFlagsSignal.signalbus_burst_count, int)
 
 
 def test_account_data(db_session):
diff --git a/tests/test_procedures.py b/tests/test_procedures.py
index 4b98377..854f223 100644
--- a/tests/test_procedures.py
+++ b/tests/test_procedures.py
@@ -128,10 +128,13 @@ def test_delete_account(account, current_ts):
         "transfer_note_max_bytes": 500,
     }
 
+    assert len(models.UpdatedLedgerSignal.query.all()) == 0
     p.process_account_update_signal(**params)
+    assert len(models.UpdatedLedgerSignal.query.all()) == 1
     with pytest.raises(p.UnsafeAccountDeletion):
         p.delete_account(C_ID, D_ID)
 
+    assert len(models.UpdatedFlagsSignal.query.all()) == 0
     latest_update_id = p.get_account_config(C_ID, D_ID).config_latest_update_id
     p.update_account_config(
         C_ID,
@@ -142,6 +145,14 @@ def test_delete_account(account, current_ts):
         config_data="",
         latest_update_id=latest_update_id + 1,
     )
+    ufs = models.UpdatedFlagsSignal.query.one()
+    assert ufs.creditor_id == C_ID
+    assert ufs.debtor_id == D_ID
+    assert ufs.config_flags == (
+        models.DEFAULT_CONFIG_FLAGS
+        | AccountData.CONFIG_SCHEDULED_FOR_DELETION_FLAG
+    )
+    assert isinstance(ufs.ts, date)
 
     config = p.get_account_config(C_ID, D_ID)
     params["last_change_seqnum"] += 1
@@ -150,12 +161,41 @@ def test_delete_account(account, current_ts):
     params["negligible_amount"] = config.negligible_amount
     params["config_flags"] = config.config_flags
     p.process_account_update_signal(**params)
+
+    assert len(models.UpdatedLedgerSignal.query.all()) == 1
+    assert len(models.UpdatedPolicySignal.query.all()) == 0
     p.process_account_purge_signal(
         debtor_id=D_ID, creditor_id=C_ID, creation_date=date(2020, 1, 15)
     )
-
     p.delete_account(C_ID, D_ID)
     assert not p.get_account(C_ID, D_ID)
+    assert len(models.UpdatedLedgerSignal.query.all()) == 2
+
+    uls = models.UpdatedLedgerSignal.query.filter_by(account_id='').one()
+    assert uls.creditor_id == C_ID
+    assert uls.debtor_id == D_ID
+    assert uls.creation_date == models.DATE0
+    assert uls.principal == 0
+    assert uls.last_transfer_number == 0
+    assert isinstance(uls.ts, date)
+
+    ups = models.UpdatedPolicySignal.query.one()
+    assert ups.creditor_id == C_ID
+    assert ups.debtor_id == D_ID
+    assert ups.policy_name is None
+    assert ups.min_principal == models.MIN_INT64
+    assert ups.max_principal == models.MAX_INT64
+    assert ups.peg_exchange_rate is None
+    assert ups.peg_debtor_id is None
+    assert isinstance(ups.ts, date)
+
+    assert len(models.UpdatedLedgerSignal.query.all()) == 2
+    ufs = models.UpdatedFlagsSignal.query.filter_by(
+        config_flags=models.DEFAULT_CONFIG_FLAGS
+    ).one()
+    assert ufs.creditor_id == C_ID
+    assert ufs.debtor_id == D_ID
+    assert isinstance(ufs.ts, date)
 
 
 def test_process_account_update_signal(account):
@@ -246,6 +286,15 @@ def get_data():
     assert ad.last_transfer_number == 22
     assert ad.last_transfer_committed_at == current_ts - timedelta(days=2)
     assert ad.config_error is None
+    uls = models.UpdatedLedgerSignal.query.one()
+    assert uls.creditor_id == C_ID
+    assert uls.debtor_id == D_ID
+    assert uls.update_id == ad.ledger_latest_update_id
+    assert uls.account_id == str(C_ID)
+    assert uls.creation_date == creation_date
+    assert uls.principal == 0
+    assert uls.last_transfer_number == 0
+    assert uls.ts == ad.ledger_latest_update_ts
 
     p.process_account_update_signal(**params)
     assert ad.last_change_seqnum == 1
@@ -295,6 +344,17 @@ def get_data():
     assert ad.ledger_principal == 0
     assert ad.ledger_last_entry_id == 89
     assert ad.ledger_last_transfer_number == 0
+    assert len(models.UpdatedLedgerSignal.query.all()) == 2
+    uls = models.UpdatedLedgerSignal.query.filter_by(
+        creation_date=creation_date + timedelta(days=2)
+    ).one()
+    assert uls.creditor_id == C_ID
+    assert uls.debtor_id == D_ID
+    assert uls.update_id == ad.ledger_latest_update_id
+    assert uls.account_id == str(C_ID)
+    assert uls.principal == 0
+    assert uls.last_transfer_number == 0
+    assert uls.ts == ad.ledger_latest_update_ts
 
     # Discard orphaned account.
     params["debtor_id"] = 1235
@@ -328,8 +388,9 @@ def get_data():
                 object_type_hint=LogEntry.OTH_ACCOUNT_LEDGER
             ).all()
         )
-        == 1
+        == 2
     )
+    assert len(models.UpdatedLedgerSignal.query.all()) == 2
 
 
 def test_process_rejected_config_signal(account):
@@ -752,7 +813,8 @@ def get_ledger_update_entries_count():
         ts=current_ts,
         ttl=10000,
     )
-    assert get_ledger_update_entries_count() == 0
+    assert get_ledger_update_entries_count() == 1
+    assert len(models.UpdatedLedgerSignal.query.all()) == 1
     assert p.get_pending_ledger_updates() == [(C_ID, D_ID)]
     assert (
         len(p.get_account_ledger_entries(C_ID, D_ID, prev=1000, count=1000))
@@ -765,6 +827,8 @@ def get_ledger_update_entries_count():
     assert p.process_pending_ledger_update(
         C_ID, 1111, max_count=max_count, max_delay=timedelta(days=10000)
     )
+    assert get_ledger_update_entries_count() == 1
+    assert len(models.UpdatedLedgerSignal.query.all()) == 1
 
     n = 0
     while not p.process_pending_ledger_update(
@@ -781,6 +845,7 @@ def get_ledger_update_entries_count():
         == 3
     )
     assert p.get_pending_ledger_updates() == []
+    assert len(models.UpdatedLedgerSignal.query.all()) == lue_count
 
     params["transfer_number"] = 21
     params["previous_transfer_number"] = 20
@@ -858,13 +923,14 @@ def get_ledger_update_entries_count():
         pass
     assert len(PendingLedgerUpdate.query.all()) == 0
     lue_count = get_ledger_update_entries_count()
-    assert lue_count == 0
+    assert lue_count == 1
+    assert len(models.UpdatedLedgerSignal.query.all()) == lue_count
     data = p.get_account_ledger(C_ID, D_ID)
     ledger_last_entry_id = data.ledger_last_entry_id
     assert data.ledger_principal == 0
     assert data.ledger_last_entry_id >= 0
     assert data.ledger_last_transfer_number == 0
-    assert data.ledger_latest_update_id == ledger_latest_update_id
+    assert data.ledger_latest_update_id == ledger_latest_update_id + 1
     assert len(PendingLedgerUpdate.query.all()) == 0
 
     max_delay = timedelta(days=10)
@@ -875,12 +941,13 @@ def get_ledger_update_entries_count():
     ):
         pass
     lue_count = get_ledger_update_entries_count()
-    assert lue_count == 1
+    assert lue_count == 2
+    assert len(models.UpdatedLedgerSignal.query.all()) == lue_count
     data = p.get_account_ledger(C_ID, D_ID)
     assert data.ledger_principal == 1000
     assert data.ledger_last_entry_id == ledger_last_entry_id + 1
     assert data.ledger_last_transfer_number == 3
-    assert data.ledger_latest_update_id == ledger_latest_update_id + 1
+    assert data.ledger_latest_update_id == ledger_latest_update_id + 2
 
 
 def test_process_rejected_direct_transfer_signal(account, current_ts):
diff --git a/tests/test_routes.py b/tests/test_routes.py
index df528a2..bfac85f 100644
--- a/tests/test_routes.py
+++ b/tests/test_routes.py
@@ -1066,11 +1066,21 @@ def test_account_config(client, account):
     r = client.patch(
         "/creditors/4294967296/accounts/1/config", json=request_data
     )
+
+    assert len(m.UpdatedPolicySignal.query.all()) == 0
     assert r.status_code == 200
     r = client.patch(
         "/creditors/4294967296/accounts/1/config", json=request_data
     )
     assert r.status_code == 200
+    ufs = m.UpdatedFlagsSignal.query.one()
+    assert ufs.debtor_id == 1
+    assert ufs.creditor_id == 4294967296
+    assert ufs.config_flags == (
+        m.DEFAULT_CONFIG_FLAGS
+        | m.AccountData.CONFIG_SCHEDULED_FOR_DELETION_FLAG
+    )
+
     data = r.get_json()
     assert data["type"] == "AccountConfig"
     assert data["uri"] == "/creditors/4294967296/accounts/1/config"
@@ -1323,6 +1333,7 @@ def test_account_exchange(client, account):
         "latestUpdateId": latestUpdateId + 1,
     }
 
+    assert len(m.UpdatedPolicySignal.query.all()) == 0
     r = client.patch(
         "/creditors/4294967296/accounts/1111/exchange", json=request_data
     )
@@ -1332,10 +1343,20 @@ def test_account_exchange(client, account):
         "/creditors/4294967296/accounts/1/exchange", json=request_data
     )
     assert r.status_code == 200
+    ups = m.UpdatedPolicySignal.query.one()
+    assert ups.debtor_id == 1
+    assert ups.creditor_id == 4294967296
+    assert ups.policy_name is None
+    assert ups.min_principal == 1000
+    assert ups.max_principal == 2000
+    assert ups.peg_exchange_rate is None
+    assert ups.peg_debtor_id is None
+
     r = client.patch(
         "/creditors/4294967296/accounts/1/exchange", json=request_data
     )
     assert r.status_code == 200
+
     data = r.get_json()
     assert data["type"] == "AccountExchange"
     assert data["uri"] == "/creditors/4294967296/accounts/1/exchange"