Quant BuffetRelax, Not Over Thinking

Market Timing Filter Applied to a Momentum and Other Factor Strategies

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Academic paper

Market Timing with Moving Averages

AuthorsPaskalis Glabadanidis

Institute
  • University of Adelaide
  • Research Network (United States)
  • ?Financial Research Network (FIRN)
  • ?University of Adelaide Business School

Strategy in a nutshell

This strategy uses AMEX, NYSE, and NASDAQ stocks, sorting them monthly into deciles based on momentum (returns from t-2 to t-12 months, skipping the last month). Deciles are value-weighted, and the highest-momentum decile is tracked. A 24-month moving average filter is applied to the equity curve of this momentum strategy. The investor goes long on the highest-momentum decile only if the equity curve’s previous month’s point exceeds its 24-month moving average. Backtesting is performed on French decile portfolios from the Kenneth French data library, though the approach can also be applied to portfolios constructed from the specified universe.

Economic rationale

Momentum strategies exploit investors’ behavioral biases, such as underreaction to new information and herding behavior, leading to price persistence over medium horizons. However, momentum performance tends to weaken during market downturns. Applying a 24-month moving average filter allows the strategy to participate only in sustained uptrends, avoiding major drawdowns when long-term momentum weakens. This timing overlay improves risk-adjusted returns by aligning exposure with favorable market regimes.

Backtest performance

Annualised return21.58%
Volatility18.69%
Beta0.453
Sharpe ratio0.94
Sortino ratio0.315
Win rate59%

Full Python code

from AlgorithmImports import *
import numpy as np
from numpy import isnan
class MarketTimingFilterAppliedMomentumOtherFactorStrategies(QCAlgorithm):
def Initialize(self):
self.SetStartDate(2000, 1, 1)
self.SetCash(100000)
market:Symbol = self.AddEquity('SPY', Resolution.Daily).Symbol

self.SMA_period:int = 24
self.period:int = 13
self.quantile:int = 10
self.leverage:int = 5
self.fundamental_count:int = 500
self.fundamental_sorting_key = lambda x: x.DollarVolume
# Equity holdings value.
self.mimic_equity_value = self.Portfolio.TotalPortfolioValue
self.holdings_value:Dict[Symbol, List[float]] = {}
self.equity_sma = SimpleMovingAverage(self.SMA_period)

# Monthly close data.
self.data:Dict[Symbol, SymbolData] = {}
self.weight:Dict[Symbol, float] = {}

self.plot = Chart('Strategy EQ')
self.plot.AddSeries(Series('EQ', SeriesType.Line, 0))

self.selection_flag:bool = False
self.Settings.MinimumOrderMarginPortfolioPercentage = 0.
self.UniverseSettings.Resolution = Resolution.Daily
self.AddUniverse(self.FundamentalSelectionFunction)
self.Schedule.On(self.DateRules.MonthEnd(market), self.TimeRules.AfterMarketOpen(market), self.Selection)
self.settings.daily_precise_end_time = False
def OnSecuritiesChanged(self, changes: SecurityChanges) -> None:
for security in changes.AddedSecurities:
    security.SetSlippageModel(CustomSlippageModel())
    security.SetFeeModel(CustomFeeModel())
    security.SetLeverage(self.leverage)

def FundamentalSelectionFunction(self, fundamental: List[Fundamental]) -> List[Symbol]:
if not self.selection_flag:
    return Universe.Unchanged
# Update the rolling window every month.
for stock in fundamental:
    symbol:Symbol = stock.Symbol
    # Store monthly price.
    if symbol in self.data:
        self.data[symbol].update(stock.AdjustedPrice)
    
selected:List[Funamental] = [
    x for x in fundamental if x.HasFundamentalData and x.Market == 'usa' \
    and not isnan(x.EarningReports.BasicAverageShares.ThreeMonths) and x.EarningReports.BasicAverageShares.ThreeMonths > 0 \
    and not isnan(x.EarningReports.BasicEPS.TwelveMonths) and x.EarningReports.BasicEPS.TwelveMonths > 0 \
    and not isnan(x.ValuationRatios.PERatio) and x.ValuationRatios.PERatio > 0
]
if len(selected) > self.fundamental_count:
    selected = [x for x in sorted(selected, key=self.fundamental_sorting_key, reverse=True)[:self.fundamental_count]]
    
performance_market_cap:Dict[Symbol, List[float]] = {}
# Warmup price rolling windows.
for stock in selected:
    symbol:Symbol = stock.Symbol
    if symbol not in self.data: 
        self.data[symbol] = SymbolData(self.period)
        history:DataFrame = self.History(symbol, self.period*30, Resolution.Daily)
        if history.empty:
            self.Log(f"Not enough data for {symbol} yet.")
            continue
        closes:Series = history.loc[symbol].close
        
        closes_len:int = len(closes.keys())
        # Find monthly closes.
        for index, time_close in enumerate(closes.items()):
            # index out of bounds check.
            if index + 1 < closes_len:
                date_month:int = time_close[0].date().month
                next_date_month:int = closes.keys()[index + 1].month
            
                # Found last day of month.
                if date_month != next_date_month:
                    self.data[symbol].update(time_close[1])

    if not self.data[symbol].is_ready():
        continue
    
    # Market cap calc.
    market_cap:float = float(stock.EarningReports.BasicAverageShares.ThreeMonths * (stock.EarningReports.BasicEPS.TwelveMonths * stock.ValuationRatios.PERatio))
    
    performance_market_cap[symbol] = [self.data[symbol].performance(), market_cap]
        
if len(performance_market_cap) <= self.quantile:
    return Universe.Unchanged

# Return sorting.
sorted_by_ret:List[Tuple[Symbol, List[float]]] = sorted(performance_market_cap.items(), key = lambda x: x[1][0], reverse = True)
quantile:int = int(len(sorted_by_ret) / self.quantile)
long:List[Tuple[Symbol, List[float]]] = [x for x in sorted_by_ret[:quantile]]

# Market cap weighting.
total_market_cap:float = sum([x[1][1] for x in long])
for symbol, perf_market_cap in long:
    self.weight[symbol] = perf_market_cap[1] / total_market_cap

return list(self.weight.keys())

def OnData(self, data: Slice) -> None:
if not self.selection_flag:
    return
self.selection_flag = False

# Trade execution
if len(self.weight) == 0: 
    self.Liquidate()
    return
stocks_invested:List[Symbol] = [x.Key for x in self.Portfolio if x.Value.Invested]
for symbol in stocks_invested:
    if symbol not in self.weight:
        self.Liquidate(symbol)

# Calculate symbol equity. - mimic trading.
for symbol, holdings in self.holdings_value.items():
    curr_price:float = self.Securities[symbol].Price
    
    holdings_price:float = holdings[0]
    holdings_q:float = holdings[1]
    fee:float = holdings_price * abs(holdings_q) * 0.00005
    slippage:float = curr_price * float(0.0001 * np.log10(2*float(abs(holdings_q))))
    
    last_holdings_value:float = holdings_price * holdings_q - fee - slippage
    new_holdings_value:float = (curr_price * holdings_q)
    trade_pl:float = (new_holdings_value - last_holdings_value)
    self.mimic_equity_value += trade_pl
self.equity_sma.Update(self.Time, self.mimic_equity_value)
self.Plot("Strategy EQ", "EQ", self.mimic_equity_value)
# self.Log('Real portfolio value: {0}; Alternative portfolio value: {1}'.format(self.Portfolio.TotalPortfolioValue, self.mimic_equity_value))
self.holdings_value.clear()

for symbol, w in self.weight.items():
    if symbol in data and data[symbol]:
        # Store symbol equity holdings. - mimic trading.
        curr_price:float = data[symbol].Value
        if curr_price != 0:
            q:float = (self.mimic_equity_value * w) / curr_price
            
            self.holdings_value[symbol] = [curr_price, q]
            if self.equity_sma.IsReady:
                if self.mimic_equity_value > self.equity_sma.Current.Value:
                    self.SetHoldings(symbol, w)
            else:
                continue
            
self.weight.clear()
def Selection(self) -> None:
self.selection_flag = True
            
class SymbolData():
def __init__(self, period: int) -> None:
self.Closes:RollingWindow = RollingWindow[float](period)

def update(self, close: float) -> None:
self.Closes.Add(close)

def is_ready(self) -> bool:
return self.Closes.IsReady

def performance(self) -> float:
closes = [x for x in self.Closes][1:]   # skip last month
return (closes[0] - closes[-1]) / closes[-1]
            
# Custom fee model.
class CustomFeeModel(FeeModel):
def GetOrderFee(self, parameters):
fee = parameters.Security.Price * parameters.Order.AbsoluteQuantity * 0.00005
return OrderFee(CashAmount(fee, "USD"))

# Custom slippage model.
class CustomSlippageModel:
def GetSlippageApproximation(self, asset, order):
# custom slippage math
slippage = asset.Price * float(0.0001 * np.log10(2*float(order.AbsoluteQuantity)))
return slippage