Trading around May option expiration is mostly a mixed bag.
Only the first day of the week (today) has a solidly bullish bias over the past 36 years. Trading the rest of the week into Friday, and the following week has historically been choppy. DJIA (NYSEARCA:DIA) has been down nineteen of the last thirty-six May expiration days with an average loss of 0.12%. The full-week has a bearish bias for DJIA and S&P 500(NYSEARCA:SPY) with records of 19 declines and 17 advances over the past 36 years. More recently, DJIA has suffered declines in seven of the past nine expiration weeks.