RE:Triple Witch DayThat's often true, but I don't think it pertains to this particular situation with K92.
Almost surely, this was a massive, coordinated effort to accumulate a large position of K92 in a hurry.
Until yesterday (Sept 18), UBS had been a relatively minor participant in the stock.
e.g. In 8-1/2 months, from Jan 2, 2020 through Sept 17, UBS added a net total of 597,562 shares, at a net cost of -$2,357,831.
Yesterday, (Sep 18), in just one day, they added a net 6,798,467 shares, at a net cost of $-53,589,480.
What is surprising, is that UBS didn't really to play until there was less than 1-3/4 hours left on the trading clock.
And ... the overwhelming portion of their shares acquisition, occurred as the clock expired.
e.g. with the clock expired, UBS acquired 3,563,210 from Anonymous, 930,200 from Morgan Stanley, 883,800 from Raymond James, 179,300 from Merrill Lynch, for a closing time total of over 5,556,510 shares ... (not including well over 100,000 from RBC + Canaccord + others)