diff --git a/zipline/data/loader_tool.py b/zipline/data/loader_tool.py
new file mode 100644
index 00000000..9fb92a9c
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+++ b/zipline/data/loader_tool.py
@@ -0,0 +1,118 @@
+#
+# Copyright 2013 Quantopian, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""
+Module for manipulating and verifying the msgpack files.
+
+Intended for testing update logic of msgpack files.
+"""
+import argparse
+import datetime
+import functools
+import itertools
+import os
+import sys
+
+import msgpack
+
+import zipline.data.loader as loader
+from zipline.utils.date_utils import tuple_to_date
+
+
+DATA_SOURCES = {
+    'benchmark': {
+        'filename': '^GSPC_benchmark.msgpack',
+        'download_func':
+        functools.partial(loader.dump_benchmarks, '^GSPC')
+    },
+    'treasury': {
+        'filename': 'treasury_curves.msgpack',
+        'download_func': loader.dump_treasury_curves
+    }
+}
+
+
+def last_date(source_name, args):
+    data = loader.get_saved_data(DATA_SOURCES[source_name]['filename'])
+    date = tuple_to_date(data[-1][0])
+    print "Last saved {source_name} date is {date}".format(
+        source_name=source_name, date=date)
+
+
+def drop_before_date(source_name, last_date):
+    """
+    Loads the msgpack file for the given @source_name and drops values
+    up to @last_date.
+
+    Used so that we can test logic that updates the msgpack's to download
+    current data if the data isn't current enough.
+    """
+    filename = DATA_SOURCES[source_name]['filename']
+    data = loader.get_saved_data(filename)
+
+    filtered_data = itertools.takewhile(
+        lambda x: tuple_to_date(x[0]).date() <= last_date.date(), data)
+
+    with loader.get_datafile(filename, mode='wb') as fp:
+        fp.write(msgpack.dumps(list(filtered_data)))
+
+
+def drop_wrapper(source_name, args):
+    if not args.last_date:
+        sys.exit("Last date must be supplied for drop.")
+    last_date = datetime.datetime.strptime(args.last_date, "%Y-%m-%d")
+
+    drop_before_date(source_name, last_date)
+
+
+def force_load(source_name, args):
+    if not os.path.exists(loader.DATA_PATH):
+        os.makedirs(loader.DATA_PATH)
+
+    filename = (DATA_SOURCES[source_name]['filename'])
+
+    filepath = os.path.join(loader.DATA_PATH, filename)
+
+    os.remove(filepath)
+    DATA_SOURCES[source_name]['download_func']()
+
+
+ACTIONS = {
+    'last_date': last_date,
+    'drop_before_date': drop_wrapper,
+    'force_load': force_load
+}
+
+
+def _make_parser():
+    parser = argparse.ArgumentParser()
+    parser.add_argument('action')
+    parser.add_argument('--data-source',
+                        action='append',
+                        choices=DATA_SOURCES.keys(),
+                        default=DATA_SOURCES.keys())
+    parser.add_argument('--last-date')
+    return parser
+
+
+def main():
+    parser = _make_parser()
+    args = parser.parse_args()
+
+    for source_name in args.data_source:
+        ACTIONS[args.action](source_name, args)
+
+if __name__ == "__main__":
+    main()