It looks like AMGN will be the one who buys ONXX,- for whatever reason they've decided it is good fit. Since initially they did not say "take it or leave it" their expectations were also that ONXX will ask for more money and, IMO, they were prepared to offer more. Instead of negotiating with them ONXX put it-self for sale publicly (maybe not that smart move...) and AMGN is pissed, and I think will offer less than it would during direct negotiations. So, for now I expect them to wait until ONXX will be fully humiliated by lack of bid from all other "interested parties" and will offer something like $133-$135...It will be interesting to see trading next few days.
(Of course, also possible, that some "unintentional" leaks will report that there are new interested parties that preparing offers and up we go!)
There are always 'sources' that leak info... I don't know how this is legal. Who knows, maybe these sources are leaked intentionally to bring the price down so that when a price is offered for $150 the % increase from where we are seems larger...who knows.