diff --git a/tests/pipeline/test_13d_filings.py b/tests/pipeline/test_13d_filings.py
new file mode 100644
index 00000000..07c5150b
--- /dev/null
+++ b/tests/pipeline/test_13d_filings.py
@@ -0,0 +1,111 @@
+"""
+Tests for the reference loader for 13d filings.
+"""
+import pandas as pd
+
+from zipline.pipeline.common import(
+    DAYS_SINCE_PREV_DISCLOSURE,
+    DISCLOSURE_DATE,
+    NUM_SHARES,
+    PERCENT_SHARES,
+    PREVIOUS_NUM_SHARES,
+    PREVIOUS_PERCENT_SHARES,
+    PREVIOUS_DISCLOSURE_DATE,
+    TS_FIELD_NAME,
+)
+from zipline.pipeline.data import _13DFilings
+from zipline.pipeline.factors.events import BusinessDaysSince13DFilingsDate
+from zipline.pipeline.loaders._13d_filings import _13DFilingsLoader
+from zipline.pipeline.loaders.utils import (
+    get_values_for_date_ranges,
+    zip_with_floats,
+    zip_with_dates
+)
+from zipline.testing.fixtures import WithPipelineEventDataLoader
+from zipline.testing.fixtures import ZiplineTestCase
+
+date_intervals = [[None, '2014-01-04'],
+                  ['2014-01-05', '2014-01-09'],
+                  ['2014-01-10', None]]
+
+empty_df = pd.DataFrame(
+    columns=[NUM_SHARES,
+             PERCENT_SHARES,
+             DISCLOSURE_DATE,
+             TS_FIELD_NAME],
+)
+
+empty_df[NUM_SHARES] = empty_df[NUM_SHARES].astype('float')
+empty_df[PERCENT_SHARES] = empty_df[PERCENT_SHARES].astype('float')
+empty_df[TS_FIELD_NAME] = empty_df[TS_FIELD_NAME].astype('datetime64[ns]')
+empty_df[DISCLOSURE_DATE] = empty_df[DISCLOSURE_DATE].astype('datetime64[ns]')
+
+_13d_filngs_cases = [
+    pd.DataFrame({
+        NUM_SHARES: [1, 15],
+        PERCENT_SHARES: [10, 20],
+        TS_FIELD_NAME: pd.to_datetime(['2014-01-05', '2014-01-10']),
+        DISCLOSURE_DATE: pd.to_datetime(['2014-01-04', '2014-01-09'])
+    }),
+    empty_df
+]
+
+
+def get_expected_previous_values(zip_date_index_with_vals,
+                                 vals,
+                                 date_intervals,
+                                 dates):
+    return pd.DataFrame({
+        0: get_values_for_date_ranges(zip_date_index_with_vals,
+                                      vals,
+                                      date_intervals,
+                                      dates),
+        1: zip_date_index_with_vals(dates, ['NaN'] * len(dates)),
+    }, index=dates)
+
+
+class _13DFilingsLoaderTestCase(WithPipelineEventDataLoader,
+                                ZiplineTestCase):
+    """
+    Test for _13_filings dataset.
+    """
+    pipeline_columns = {
+        PREVIOUS_NUM_SHARES:
+            _13DFilings.number_shares.latest,
+        PREVIOUS_PERCENT_SHARES:
+            _13DFilings.percent_shares.latest,
+        PREVIOUS_DISCLOSURE_DATE:
+            _13DFilings.disclosure_date.latest,
+        DAYS_SINCE_PREV_DISCLOSURE:
+            BusinessDaysSince13DFilingsDate(),
+    }
+
+    @classmethod
+    def get_sids(cls):
+        return range(2)
+
+    @classmethod
+    def get_dataset(cls):
+        return {sid: frame
+                for sid, frame
+                in enumerate(_13d_filngs_cases)}
+
+    loader_type = _13DFilingsLoader
+
+    def setup(self, dates):
+        cols = {}
+        cols[
+            PREVIOUS_DISCLOSURE_DATE
+        ] = get_expected_previous_values(zip_with_dates,
+                                         ['NaT', '2014-01-04', '2014-01-09'],
+                                         date_intervals, dates)
+        cols[PREVIOUS_NUM_SHARES] = get_expected_previous_values(
+            zip_with_floats, ['NaN', 1, 15], date_intervals, dates
+        )
+        cols[PREVIOUS_PERCENT_SHARES] = get_expected_previous_values(
+            zip_with_floats, ['NaN', 10, 20], date_intervals, dates
+        )
+        cols[DAYS_SINCE_PREV_DISCLOSURE] = self._compute_busday_offsets(
+            cols[PREVIOUS_DISCLOSURE_DATE]
+        )
+        return cols
diff --git a/zipline/pipeline/common.py b/zipline/pipeline/common.py
index f6dd4c8f..6c78038d 100644
--- a/zipline/pipeline/common.py
+++ b/zipline/pipeline/common.py
@@ -9,10 +9,12 @@ CASH_AMOUNT_FIELD_NAME = 'cash_amount'
 COUNT_FIELD_NAME = 'count'
 BUYBACK_ANNOUNCEMENT_FIELD_NAME = 'buyback_date'
 DAYS_SINCE_PREV = 'days_since_prev'
+DAYS_SINCE_PREV_DISCLOSURE = 'days_since_prev_disclosure'
 DAYS_SINCE_PREV_DIVIDEND_ANNOUNCEMENT = 'days_since_prev_dividend_announcement'
 DAYS_SINCE_PREV_EX_DATE = 'days_since_prev_ex_date'
 DAYS_TO_NEXT = 'days_to_next'
 DAYS_TO_NEXT_EX_DATE = 'days_to_next_ex_date'
+DISCLOSURE_DATE = 'disclosure_date'
 EX_DATE_FIELD_NAME = 'ex_date'
 FISCAL_QUARTER_FIELD_NAME = 'fiscal_quarter'
 FISCAL_YEAR_FIELD_NAME = 'fiscal_year'
@@ -29,23 +31,28 @@ NEXT_HIGH = 'next_high'
 NEXT_LOW = 'next_low'
 NEXT_MEAN = 'next_mean'
 NEXT_PAY_DATE = 'next_pay_date'
+NUM_SHARES = 'number_shares'
 NEXT_RELEASE_DATE = 'next_release_date'
 NEXT_STANDARD_DEVIATION = 'next_standard_deviation'
 PAY_DATE_FIELD_NAME = 'pay_date'
+PERCENT_SHARES = 'percent_shares'
 PREVIOUS_ACTUAL_VALUE = 'previous_actual_value'
 PREVIOUS_AMOUNT = 'previous_amount'
 PREVIOUS_ANNOUNCEMENT = 'previous_announcement'
 PREVIOUS_BUYBACK_ANNOUNCEMENT = 'previous_buyback_announcement'
 PREVIOUS_BUYBACK_CASH = 'previous_buyback_cash'
 PREVIOUS_BUYBACK_SHARE_COUNT = 'previous_buyback_share_count'
+PREVIOUS_DISCLOSURE_DATE = 'previous_disclosure_date'
 PREVIOUS_COUNT = 'previous_count'
 PREVIOUS_EX_DATE = 'previous_ex_date'
+PREVIOUS_NUM_SHARES = 'previous_number_shares'
 PREVIOUS_FISCAL_QUARTER = 'previous_fiscal_quarter'
 PREVIOUS_FISCAL_YEAR = 'previous_fiscal_year'
 PREVIOUS_HIGH = 'previous_high'
 PREVIOUS_LOW = 'previous_low'
 PREVIOUS_MEAN = 'previous_mean'
 PREVIOUS_PAY_DATE = 'previous_pay_date'
+PREVIOUS_PERCENT_SHARES = 'previous_percentage'
 PREVIOUS_RELEASE_DATE = 'previous_release_date'
 PREVIOUS_STANDARD_DEVIATION = 'previous_standard_deviation'
 RELEASE_DATE_FIELD_NAME = 'release_date'
diff --git a/zipline/pipeline/data/_13d_filings.py b/zipline/pipeline/data/_13d_filings.py
new file mode 100644
index 00000000..891d25f1
--- /dev/null
+++ b/zipline/pipeline/data/_13d_filings.py
@@ -0,0 +1,15 @@
+"""
+Dataset representing recently disclosed 13d filings.
+"""
+from zipline.utils.numpy_utils import datetime64ns_dtype, float64_dtype
+
+from .dataset import Column, DataSet
+
+
+class _13DFilings(DataSet):
+    """
+    Dataset representing dates of recently disclosed 13d filings.
+    """
+    number_shares = Column(float64_dtype)
+    percent_shares = Column(float64_dtype)
+    disclosure_date = Column(datetime64ns_dtype)
diff --git a/zipline/pipeline/data/__init__.py b/zipline/pipeline/data/__init__.py
index 545088dd..241cbb85 100644
--- a/zipline/pipeline/data/__init__.py
+++ b/zipline/pipeline/data/__init__.py
@@ -1,3 +1,4 @@
+from ._13d_filings import _13DFilings
 from .buyback_auth import CashBuybackAuthorizations, ShareBuybackAuthorizations
 from .dividends import (
     DividendsByAnnouncementDate,
@@ -10,6 +11,7 @@ from .equity_pricing import USEquityPricing
 from .dataset import DataSet, Column, BoundColumn
 
 __all__ = [
+    '_13DFilings',
     'BoundColumn',
     'CashBuybackAuthorizations',
     'Column',
diff --git a/zipline/pipeline/factors/__init__.py b/zipline/pipeline/factors/__init__.py
index 9b098d59..d6d32b98 100644
--- a/zipline/pipeline/factors/__init__.py
+++ b/zipline/pipeline/factors/__init__.py
@@ -5,6 +5,7 @@ from .factor import (
     RecarrayField,
 )
 from .events import (
+    BusinessDaysSince13DFilingsDate,
     BusinessDaysSinceCashBuybackAuth,
     BusinessDaysSinceDividendAnnouncement,
     BusinessDaysUntilNextExDate,
@@ -28,6 +29,7 @@ from .technical import (
 )
 
 __all__ = [
+    'BusinessDaysSince13DFilingsDate',
     'BusinessDaysSinceCashBuybackAuth',
     'BusinessDaysSinceDividendAnnouncement',
     'BusinessDaysUntilNextExDate',
diff --git a/zipline/pipeline/factors/events.py b/zipline/pipeline/factors/events.py
index 286cfafa..972d2a5c 100644
--- a/zipline/pipeline/factors/events.py
+++ b/zipline/pipeline/factors/events.py
@@ -4,6 +4,7 @@ announcements, acquisitions, dividends, etc.).
 """
 from numpy import newaxis
 from ..data import (
+    _13DFilings,
     CashBuybackAuthorizations,
     ShareBuybackAuthorizations,
     DividendsByAnnouncementDate,
@@ -203,3 +204,14 @@ class BusinessDaysSincePreviousExDate(
     zipline.pipeline.factors.BusinessDaysSinceDividendAnnouncement
     """
     inputs = [DividendsByExDate.previous_date]
+
+
+class BusinessDaysSince13DFilingsDate(
+    BusinessDaysSincePreviousEvents
+):
+    """
+    Factor returning the number of **business days** (not trading days!) since
+    the most recent 13d filings for each asset.
+
+    """
+    inputs = [_13DFilings.disclosure_date]
diff --git a/zipline/pipeline/loaders/_13d_filings.py b/zipline/pipeline/loaders/_13d_filings.py
new file mode 100644
index 00000000..ad35bf77
--- /dev/null
+++ b/zipline/pipeline/loaders/_13d_filings.py
@@ -0,0 +1,54 @@
+"""
+Reference implementation for 13d filings loaders.
+"""
+
+from zipline.pipeline.common import (
+    DISCLOSURE_DATE,
+    PERCENT_SHARES,
+    NUM_SHARES
+)
+from zipline.pipeline.data import _13DFilings
+from zipline.pipeline.loaders.events import EventsLoader
+from zipline.utils.memoize import lazyval
+
+
+class _13DFilingsLoader(EventsLoader):
+    """
+    Reference loader for
+    :class:`zipline.pipeline.data._13DFilings`.
+
+    events_by_sid: dict[sid -> pd.DataFrame(knowledge date,
+    disclosure date, percent shares, number of shares)]
+
+    """
+    expected_cols = frozenset([DISCLOSURE_DATE,
+                               PERCENT_SHARES,
+                               NUM_SHARES])
+    event_date_col = DISCLOSURE_DATE
+
+    def __init__(self, all_dates, events_by_sid,
+                 infer_timestamps=False,
+                 dataset=_13DFilings):
+        super(_13DFilingsLoader, self).__init__(
+            all_dates, events_by_sid, infer_timestamps, dataset=dataset,
+        )
+
+    @lazyval
+    def disclosure_date_loader(self):
+        return self._previous_event_date_loader(
+            self.dataset.disclosure_date,
+        )
+
+    @lazyval
+    def percent_shares_loader(self):
+        return self._previous_event_value_loader(
+            self.dataset.percent_shares,
+            PERCENT_SHARES
+        )
+
+    @lazyval
+    def number_shares_loader(self):
+        return self._previous_event_value_loader(
+            self.dataset.number_shares,
+            NUM_SHARES
+        )
diff --git a/zipline/pipeline/loaders/__init__.py b/zipline/pipeline/loaders/__init__.py
index 6c717b0e..aeb5635e 100644
--- a/zipline/pipeline/loaders/__init__.py
+++ b/zipline/pipeline/loaders/__init__.py
@@ -1,3 +1,4 @@
+from ._13d_filings import _13DFilingsLoader
 from .earnings import EarningsCalendarLoader
 from .consensus_estimates import ConsensusEstimatesLoader
 from .buyback_auth import (
@@ -12,6 +13,7 @@ from .dividends import (
 from .equity_pricing_loader import USEquityPricingLoader
 
 __all__ = [
+    '_13DFilingsLoader',
     'CashBuybackAuthorizationsLoader',
     'DividendsByAnnouncementDateLoader',
     'DividendsByExDateLoader',
diff --git a/zipline/pipeline/loaders/blaze/_13d_filings.py b/zipline/pipeline/loaders/blaze/_13d_filings.py
new file mode 100644
index 00000000..d6502d64
--- /dev/null
+++ b/zipline/pipeline/loaders/blaze/_13d_filings.py
@@ -0,0 +1,68 @@
+from zipline.pipeline.common import (
+    SID_FIELD_NAME,
+    TS_FIELD_NAME,
+    PERCENT_SHARES,
+    NUM_SHARES,
+    DISCLOSURE_DATE)
+from zipline.pipeline.data import _13DFilings
+from zipline.pipeline.loaders import _13DFilingsLoader
+from .events import BlazeEventsLoader
+
+
+class Blaze_13DFilingsLoader(BlazeEventsLoader):
+    """A pipeline loader for the ``_13DFilings`` dataset that
+    loads data from a blaze expression.
+
+    Parameters
+    ----------
+    expr : Expr
+        The expression representing the data to load.
+    resources : dict, optional
+        Mapping from the atomic terms of ``expr`` to actual data resources.
+    odo_kwargs : dict, optional
+        Extra keyword arguments to pass to odo when executing the expression.
+    data_query_time : time, optional
+        The time to use for the data query cutoff.
+    data_query_tz : tzinfo or str
+        The timezeone to use for the data query cutoff.
+    dataset: DataSet
+        The DataSet object for which this loader loads data.
+
+    Notes
+    -----
+    The expression should have a tabular dshape of::
+
+       Dim * {{
+           {SID_FIELD_NAME}: int64,
+           {TS_FIELD_NAME}: datetime,
+           {PERCENTAGE}: float64,
+           {NUM_SHARES}: float64,
+           {DISCLOSURE_DATE}: ?datetime,
+       }}
+
+    Where each row of the table is a record including the sid to identify the
+    company, the timestamp where we learned about the disclosure, the
+    date of the disclosure, the percentage, and the number of shares.
+
+    If the '{TS_FIELD_NAME}' field is not included it is assumed that we
+    start the backtest with knowledge of all disclosures.
+    """
+
+    __doc__ = __doc__.format(
+        TS_FIELD_NAME=TS_FIELD_NAME,
+        SID_FIELD_NAME=SID_FIELD_NAME,
+        PERCENTAGE=PERCENT_SHARES,
+        NUM_SHARES=NUM_SHARES,
+        DISCLOSURE_DATE=DISCLOSURE_DATE
+    )
+
+    _expected_fields = frozenset({
+        TS_FIELD_NAME,
+        SID_FIELD_NAME,
+        PERCENT_SHARES,
+        NUM_SHARES,
+        DISCLOSURE_DATE
+    })
+
+    concrete_loader = _13DFilingsLoader
+    concrete_dataset = _13DFilings
diff --git a/zipline/pipeline/loaders/blaze/__init__.py b/zipline/pipeline/loaders/blaze/__init__.py
index 9fec0579..74922685 100644
--- a/zipline/pipeline/loaders/blaze/__init__.py
+++ b/zipline/pipeline/loaders/blaze/__init__.py
@@ -1,4 +1,4 @@
-
+from ._13d_filings import Blaze_13DFilingsLoader
 from .buyback_auth import (
     BlazeCashBuybackAuthorizationsLoader,
     BlazeShareBuybackAuthorizationsLoader
@@ -20,6 +20,7 @@ from .earnings import (
 from .consensus_estimates import BlazeConsensusEstimatesLoader
 
 __all__ = (
+    'Blaze_13DFilingsLoader',
     'BlazeCashBuybackAuthorizationsLoader',
     'BlazeDividendsByAnnouncementDateLoader',
     'BlazeConsensusEstimatesLoader',