Buybacks seem to deter takeovers.

Newswise Business News | Researcher Finds Good Management, Open Market Stock Buy-backs Deter Takeover Attempts:

"Firms that buy their stock back on the open market are seen as more efficient and more sensitive to shareholder interests,” said Matt Billett, professor of finance in the Tippie College of Business. “It’s a sign of shareholder-friendly management.”

Billett recently studied more than 23,000 U.S. companies to determine whether open market share repurchases deter takeovers. What he and his co-author found was evidence that, for the first time, verified the conventional wisdom that, indeed, they do.

“While tender offers have been shown to act as an effective defense in the midst of takeover battles, open market repurchases may deter unwanted bids, pre-empting would-be acquirers from bidding in the first place,” Billett said"

Very interesting. Will definitely find its was into class. A working paper version of the actual paper is here.