1. Buyer: Amgen
Target: Onyx
Price: $10.4 billion

As analysts put it before the Onyx buyout, the California-based company was one of just a handful of smaller drugmakers with enough revenue and revenue potential to "move the needle" for big biopharma companies. So when Amgen ($AMGN) first came calling last summer with a $10 billion bid, Onyx spurned it to hold out for a better offer.

Amgen did ultimately prevail, with Onyx's price reportedly scaring off would-be buyers like Pfizer ($PFE). Amgen CEO Robert Bradway haggled down the cost somewhat by requesting interim trial data he knew Onyx couldn't reveal; when the company refused to unblind its Phase III study, he used it as grounds to pare down his next bid. Not long after, the two sides reached a deal somewhere in the middle.

At the center of that deal was Kyprolis, the hot-selling blood cancer med that scored $64 million between its July 2012 launch and the end of that year--despite competition from Celgene's ($CELG) Revlimid and Johnson & Johnson's ($JNJ) Velcade. With four studies to support and extend Kyprolis' market position ongoing, analysts have predicted the multiple myeloma drug will generate $2.4 billion in 2019, with some thinking it will reach as high as $3 billion at its peak.

Whatever Kyprolis does churn out will take the pressure off Amgen's older meds, some of which--like anemia drug Epogen--now face biosimilar competition.

For more:
Special Reports: Top 15 Drug Launch Superstars - Kyprolis | Top 20 orphan drugs by 2018 - Kyprolis
Amgen CEO scored Onyx with unorthodox M&A move
Amgen nabs Onyx for $10.4B. What's next for Kyprolis?
Onyx hands bidders new Kyprolis data to smooth path to $9.5B deal
Onyx CEO dismisses rumors that Amgen alone is still in the hunt
Report: Pfizer backs off Onyx bid as price gets too rich
Onyx puts out 'for sale' sign after rejecting $10B Amgen bid

-- Carly Helfand (email | Twitter)