Momentum Effect in Stocks Combined with Stop-Losses
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Taming Momentum Crashes: A Simple Stop-Loss Strategy
Yufeng Han; Guofu Zhou
- University of North Carolina at Charlotte
- ?University of North Carolina (UNC) at Charlotte - Finance
- Washington University in St. Louis
- ?Washington University in St. Louis - John M. Olin Business School
Strategy in a nutshell
This strategy invests in NYSE, AMEX, and NASDAQ stocks above $5, excluding CEFs, REITs, ADRs, foreign stocks, and the smallest size decile. Monthly, the top 10% of stocks by 6-month returns (with a one-month skip) are selected, and the portfolio is value-weighted with a 10% stop-loss per stock. Stocks hitting the stop-loss are sold, and cash is held until the next rebalance.
Economic rationale
Momentum profits from investors’ tendency to overreact to past information, which gradually corrects. Using stop-losses helps limit downside risk, improving the strategy’s risk/return profile while still capitalizing on momentum opportunities.
Backtest performance
Annualised return18.72%
Volatility20.99%
Beta0.381
Sharpe ratio0.89
Sortino ratio0.16
Win rate31%
Full Python code
import numpy as np
from AlgorithmImports import *
class MomentumEffectStocksCombinedStopLosses(QCAlgorithm):
def Initialize(self):
self.SetStartDate(2000, 1, 1)
self.SetCash(100000)
self.period:int = 7
self.leverage:int = 10
self.quantile:int = 10
self.exchange_codes:List[str] = ['NYS', 'NAS', 'ASE']
market:Symbol = self.AddEquity('SPY', Resolution.Daily).Symbol
self.fundamental_count:int = 500
self.fundamental_sorting_key = lambda x: x.DollarVolume
# Symbol data.
self.data:Dict[Symbol, SymbolData] = {}
self.weight:Dict[Symbol, float] = {}
# Opened stop-orders.
self.opened_orders:List[OrderTicket] = []
self.last_month:int = -1
self.selection_flag:bool = False
self.UniverseSettings.Resolution = Resolution.Daily
self.AddUniverse(self.FundamentalSelectionFunction)
self.settings.daily_precise_end_time = False
self.settings.minimum_order_margin_portfolio_percentage = 0.
self.schedule.on(self.date_rules.month_start(market),
self.time_rules.after_market_open(market),
self.selection)
def OnSecuritiesChanged(self, changes: SecurityChanges) -> None:
for security in changes.AddedSecurities:
symbol:Symbol = security.Symbol
security.SetFeeModel(CustomFeeModel())
security.SetLeverage(self.leverage)
if symbol not in self.data:
self.data[symbol] = SymbolData(self.period)
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[Fundamental] = [x for x in fundamental if x.HasFundamentalData and x.Market == 'usa' and x.MarketCap != 0 and \
x.SecurityReference.ExchangeId in self.exchange_codes and x.CompanyReference.IsREIT == 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:Dict[Fundamental, float] = {}
# Warmup price rolling windows.
for stock in fundamental:
symbol:Symbol = stock.Symbol
if symbol not in self.data:
self.data[symbol] = SymbolData(self.period)
history = self.History(symbol, self.period*30, Resolution.Daily)
if history.empty:
self.Log(f"Not enough data for {symbol} yet.")
continue
closes = history.loc[symbol].close
closes_len = 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 = time_close[0].date().month
next_date_month = closes.keys()[index + 1].month
# Found last day of month.
if date_month != next_date_month:
self.data[symbol].update(time_close[1])
if self.data[symbol].is_ready():
performance[stock] = self.data[symbol].performance()
# Performance sorting.
if len(performance) >= self.quantile:
sorted_by_return:List = sorted(performance.items(), key = lambda x: x[1], reverse = True)
quantile:int = int(len(sorted_by_return) / self.quantile)
long:List[Fundamental] = [x[0] for x in sorted_by_return[:quantile]]
# Market cap weighting.
mc_sum:float = sum([x.MarketCap for x in long])
for stock in long:
self.weight[stock.Symbol] = stock.MarketCap / mc_sum
return list(self.weight.keys())
def OnData(self, data: Slice) -> None:
if not self.selection_flag:
return
self.selection_flag = False
# Trade execution.
for symbol, w in self.weight.items():
if symbol in data.Keys and data[symbol]:
curr_price:float = data[symbol].Value
if curr_price != 0:
# Unit size calc.
unit_size:float = self.CalculateOrderQuantity(symbol, w)
# Buy order.
if unit_size != 0:
self.MarketOrder(symbol, unit_size)
# SL setting.
sl_price:float = curr_price * 0.95 # 5% SL.
ticket:OrderTicket = self.StopMarketOrder(symbol, -unit_size, sl_price, 'SL')
self.opened_orders.append(ticket)
self.weight.clear()
def selection(self) -> None:
self.selection_flag = True
# Liquidate and cancel pending orders.
self.Liquidate()
for ticket_index in range(len(self.opened_orders)-1, 0, -1):
response = self.opened_orders[ticket_index].Cancel("Canceled Trade")
self.opened_orders.remove(self.opened_orders[ticket_index])
class SymbolData():
def __init__(self, period: int):
self._price:RollingWindow = RollingWindow[float](period)
def update(self, price: float) -> None:
self._price.Add(price)
def is_ready(self) -> bool:
return self._price.IsReady
# 12 month momentum, one month skipped.
def performance(self) -> float:
return self._price[1] / self._price[self._price.Count - 1] - 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"))