diff --git a/__init__.py b/__init__.py
index a11da2c..b4c75e7 100644
--- a/__init__.py
+++ b/__init__.py
@@ -10,10 +10,12 @@ from .reconciliation import Reconciliation
 from .line import Line
 from .splitline import SplitLine
 from .assetsetting import AssetSetting
+from .asset import AssetRate
 
 
 def register():
     Pool.register(
+        AssetRate,
         Type,
         Book,
         Line,
diff --git a/asset.py b/asset.py
new file mode 100644
index 0000000..9505d2f
--- /dev/null
+++ b/asset.py
@@ -0,0 +1,48 @@
+# -*- coding: utf-8 -*-
+# This file is part of the cashbook-module from m-ds.de for Tryton.
+# The COPYRIGHT file at the top level of this repository contains the
+# full copyright notices and license terms.
+
+from trytond.pool import Pool, PoolMeta
+CACHEKEY_ASSETRATE = 'assetrate-%s'
+
+
+class AssetRate(metaclass=PoolMeta):
+    __name__ = 'investment.rate'
+
+    @classmethod
+    def create(cls, vlist):
+        """ update cache-value
+        """
+        MemCache = Pool().get('cashbook.memcache')
+
+        records = super(AssetRate, cls).create(vlist)
+        for rate in records:
+            MemCache.record_update(CACHEKEY_ASSETRATE % rate.asset.id, rate)
+        return records
+
+    @classmethod
+    def write(cls, *args):
+        """ update cache-value
+        """
+        MemCache = Pool().get('cashbook.memcache')
+
+        super(AssetRate, cls).write(*args)
+
+        actions = iter(args)
+        for rates, values in zip(actions, actions):
+            for rate in rates:
+                MemCache.record_update(CACHEKEY_ASSETRATE % rate.asset.id, rate)
+
+    @classmethod
+    def delete(cls, records):
+        """ set cache to None
+        """
+        MemCache = Pool().get('cashbook.memcache')
+
+        for record in records:
+            MemCache.record_update(CACHEKEY_ASSETRATE % record.asset.id, None)
+        super(AssetRate, cls).delete(records)
+
+# end
+
diff --git a/book.py b/book.py
index c88563a..949c331 100644
--- a/book.py
+++ b/book.py
@@ -16,6 +16,7 @@ from sql.functions import CurrentDate
 from sql.aggregate import Sum
 from sql.conditionals import Case, Coalesce
 from trytond.modules.cashbook.model import CACHEKEY_CURRENCY
+from .asset import CACHEKEY_ASSETRATE
 
 
 class Book(SymbolMixin, metaclass=PoolMeta):
@@ -288,6 +289,7 @@ class Book(SymbolMixin, metaclass=PoolMeta):
                         }, {
                             'model': 'investment.rate',
                             'query': [('asset.id', '=', x.asset.id)],
+                            'cachekey': CACHEKEY_ASSETRATE % x.asset.id,
                         } if x.asset is not None else {}],
                     addkeys = [query_date.isoformat()])
                 for x in cashbooks
@@ -426,6 +428,7 @@ class Book(SymbolMixin, metaclass=PoolMeta):
                         }, {
                             'model': 'investment.rate',
                             'query': [('asset.id', '=', x.asset.id)],
+                            'cachekey': CACHEKEY_ASSETRATE % x.asset.id,
                         } if x.asset is not None else {}],
                     addkeys=[
                             str(company_currency),