The “For Sale” sign officially went up outside Millipore Corp. (NYSE:MIL).

Responding to speculation that it’s the target of a $6 billion buyout offer, executives at the Billerica, Mass.-based maker of bioscience equipment late Feb. 23 confirmed they hired Goldman Sachs to assist them in “evaluating strategic alternatives, including pursuing a process with potential bidders to explore a possible merger or sale of the company.”

Millipore was put in play this week after news reports surfaced that Thermo Fisher Scientific Inc. (NYSE:TMO) was preparing a bid to purchase its smaller rival. Spokespersons at both companies previously had declined to comment about a possible deal, which would value Millipore at about $106.50 a share — or a nearly 50 percent premium to the company’s stock price prior to the buyout rumors. The stock closed Feb. 23 at $88.87 a share.

In a statement, Millipore also said it has retained Cravath, Swaine & Moore LLP as its legal advisor. The New York-based legal shop has represented a large number of Wall Street heavyweights on both sides of acquisition talks, including recent deals involving IBM, Kraft Foods and UAL, the parent company of United Airlines.

Millipore officials said there is no timetable for completing the evaluation process, adding that they do not intend to make any other statements unless the company’s board of directors approves a specific transaction.