S&P 100 Long Strategy During Option Expiry Week

“Investors select S&P 100 index stocks as their universe (easily tracked via ETF/index fund). Long positions are taken during option-expiration week; cash is held otherwise.”

ASSET CLASS: CFDs, ETFs, futures, stocks | REGION: United States | FREQUENCY: Weekly | MARKET:
equities | KEYWORD: Option, Expiration

I. STRATEGY IN A NUTSHELL

Investors choose stocks from the S&P 100 index as his/her investment universe (stocks could be easily tracked via ETF or index fund). He/she then goes long S&P 100 stocks during the option-expiration week and stays in cash during other days.

II. ECONOMIC RATIONALE

Academic research suggests that intra-month weekly patterns in call-related activity contribute to patterns in weekly average equity returns. Hedge rebalancing by option market makers in the largest stocks with the most actively traded options is the main reason for the abnormal stock’s returns. During option-expiration weeks, a sizable reduction occurs in option-open interest as the near-term options approach expiration and then expire. A reduction in call-open interest should be associated with a reduction in the net long call position of market makers. This implies a decrease in the short-stock positions being held by market makers to delta hedge their long call holdings.

III. SOURCE PAPER

Returns and Option Activity over the Option-Expiration Week for S&P 100 Stocks [Click to Open PDF]

Chris T. Stivers, University of Louisville ; icheng Sun, Old Dominion University

<Abstract>

For S&P 100 stocks, we find that the weekly returns over option-expiration (OE) weeks (a month’s third-Friday week) tend to be high, relative to: (1) the third-Friday weekly returns of other stocks with less option activity, (2) the own stock’s other weekly returns, (3) the risk, based on asset-pricing alphas. For these same stocks, a month’s fourth-Friday weekly returns underperform modestly. We suggest the following two avenues are likely partial contributors towards understanding these return patterns: (1) delta-hedge rebalancing by option market makers, with a reduction in short-stock hedge positions over the OE week, and (2) declining risk perceptions over the OE week, as measured by option-derived implied volatilities. Our findings suggest option activity can induce reliable patterns in the weekly returns of option-active large-cap stocks.

IV. BACKTEST PERFORMANCE

Annualised Return	9.3%
Volatility	8.7%
Beta	0.128
Sharpe Ratio	0.119
Sortino Ratio	0.056
Maximum Drawdown	15.1%
Win Rate	61%

V. FULL PYTHON CODE

from AlgoLib import *

class OptionExpirationWeekEffect(XXX):

    def Initialize(self):
        self.SetStartDate(2010, 1, 1)
        self.SetCash(10000)

        self.symbol = self.AddEquity("OEF", Resolution.Minute).Symbol
        
        option = self.AddOption("OEF")
        option.SetFilter(-3, 3, timedelta(0), timedelta(days = 60))       

        self.SetBenchmark("OEF")
        self.near_expiry = datetime.min
        
        self.Schedule.On(self.DateRules.Every(DayOfWeek.Monday, DayOfWeek.Monday), self.TimeRules.AfterMarketOpen(self.symbol, 1), self.Rebalance)

    def OnData(self, slice):
        if self.Time.date() == self.near_expiry.date():
            self.Liquidate()

    def Rebalance(self):
        calendar = self.TradingCalendar.GetDaysByType(TradingDayType.OptionExpiration, self.Time, self.EndDate)
        expiries = [i.Date for i in calendar]
        if len(expiries) == 0: return

        self.near_expiry = expiries[0]

        if (self.near_expiry - self.Time).days <= 5:
            self.SetHoldings(self.symbol, 1)