LEXINGTON,
Mass. (AP) — Shares of Amag Pharmaceuticals
Inc. jumped today in premarket trading, after the drugmaker said it received an
unsolicited buyout offer worth $381 million from MSMB Capital Management.

Amag, based in Lexington,
Mass., said MSMB proposed to buy
all of its outstanding stock for $18 per share in cash. That represents a
25-percent premium over the stock’s closing price Tuesday of $14.39.

Amag, which makes Feraheme for the treatment of iron
deficiency anemia in adults with chronic kidney disease, said its board will
carefully consider the proposal.

Shares climbed 14.7 percent, or $2.11, to $16.50 in
pre-market trading.

Last month, Amag said it will buy drugmaker Allos
Therapeutics Inc. for about $268 million in stock. The deal is designed to
bolster its commercial portfolio and cuts costs. That deal is expected to close
in the fourth quarter.

Under terms of that deal, Allos stockholders will get 0.1282
shares of Amag stock for each share of Allos. Amag shareholders will own about
61 percent of the combined company, while Allos stockholders will have 39
percent.

Amag will nominate five of the nine members of the new
company’s board, and its CEO, Dr. Brian J.G. Pereira, will serve as CEO of the
new company. Michael Narachi will remain chairman. The combined company will be
based in Lexington, Mass.