Yes, if yer going to narrow it down to "equity markets", then if ye be speaking of US equity, I'd echo Stockolio above...The last hour, and more specifically the final 15 minutes, from 3:45 PM ET onward.
Reports and last 25 minutes of day session of most markets. One is to add more size and other less size.
00:00 Go to bed!! ("Fergawdsakes!") 03:30 European Open (Check your local listings.) 08:30 Major Economic Releases (YMMV) 09:30 Cash Market Open ("Idiot Hour I" which is ~30 minutes long...) 10:00 Morning Continues... 11:30 Euro-close (from ~11:20, Euro-capital wants to buy or sell their positions into U.S. mkt.) 11:45 Lunch Doldrums (ATR goes to crap, watch 4 Euro-close agenda REVERSE, return in 90 minutes.) 13:15 Afternoon Session 15:20 Closing Pressures ("Idiot Hour II." Time to finish the day's agenda -- whether in buoys or sinks the mkt.) 15:40 GET OUT. 16:00 Cash Equities Mkt Closes. 16:15 Futures Close (nearly.) 20:30 Asia Open begins I. 21:30 Asia Open begins II. So, your best times for targeted volume are ~2 hours in the morning, and ~2 hours in the afternoon.
Thanks for the answers. But i was thinking more granular. ie, prime brokers start calling clients regarding margin related issues around 2:45pm. 3:00 - 3:35pm all block/MOC orders need to be communicated with prime broker. there are skittish moves around those times. hedge funds use the info to trade the last 1hour 15 minutes into the close based upon the info, etc. Day traders refer to various important intra day times but I don't have any idea why those times are important?