Years ago I would hear about...Beware of triple witching hour. The 4 times per year when all options would have an expiration on that date. Now so many more stocks have weekly dates, monthly dates. Just wondering if these Fridays (and Saturdays) are as strong (for moving the market) as they were 10 or more years ago...??
Download a few years of SPY historical data. Link: Yahoo Finance SPY Historical Data Study the dates you are interested in. Do you see any unusual volatility on those dates? You will notice nothing out of the ordinary - just regular trading days.
They gave it a catchy/exciting/scary sounding name, and therefore has always result in more in spilled over it than it strictly deserved in my opinion. If reporters just had to call it "One of the 4 times a year all options expire" only the geekiest of us would even know about it.
Used to be "everything happened/expired" at once.... caused large and volatile swings. Some years ago the exchanges decided to "spread the expiration around"....since then triple witch expiration has effectively been a non-event.
%% You may still see fri big volume[ i do] but not so much vol.....AS a practical matter,dont see much price difference, in liquid markets