If that is the case, then could they have taken part in the intial sale at all?
good question and hopefully one of the smarter posters (particularly lawyers) can respond. i think if there was something material (using the legal definition) then it would have to be disclosed to those purchasing shares - in fact i would be surprised if there weren't specific regulations governing offerings and disclosure. but defining "material" in the legal sense is not easy - and clearly early stage negotiations are not material. so then is the udnerwriter able to undertake transactions if information is not "material". legally yes, BUT most investment houses have internal guidelines governing when they are allowed to engage in transactions, and often these rules are much stricter than the legal definition of "material information", so it is plausible that UBS is getting some early MNTA business in one form or another that internally precludes transactions in MNTA but would not meet the legal definition of "material" to preclude a stock offering best response i can come up with as a non-lawyer:)
PS: i missed all the hoopla, spike, etc. - downside of having a day job! PPS: i have some trading shares but still would not have sold at 15.6 so no biggie