Lilly Boosts Bid for Icos

The most prominent objection to the deal has come from HealthCor Management LP, an investment management firm that now owns 6% if Icos shares. Although HealthCor isn't the biggest Icos investor, the firm sent a letter to Icos directors in mid-November saying Lilly should pay "well in excess" of $40 a share.

No other large shareholders have complained about the deal publicly, at least according to filings with the Securities and Exchange Commission. One independent proxy research firm supported the original deal, but another firm opposed it.

In another pharmaceutical industry takeover update Monday, the German drug and chemical conglomerate Merck KGaA said European Union antitrust regulators have approved its takeover of Swiss biotechnology company Serono(SRA Quote). U.S. regulators cleared the deal Oct. 30.

Merck, which announced its offer in September, will pay $13.3 billion for the company whose biggest product is the multiple sclerosis drug Rebif.