Apple disclosed in a regulatory filing that it will pay $8 for each share of AuthenTec, a 58 percent premium to thei closing price on Thursday.
AuthenTec's stock jumped $3.30, or 65 percent, to $8.37 in Friday afternoon trading - above the offered price.
The transaction was unanimously approved by AuthenTec's board. It still requires approval from a majority of the holders of AuthenTec stock. AuthenTec currently has about 44.5 million outstanding shares, according to FactSet.
Shares of Apple Inc., based in Cupertino, Calif., gained $4.70 to $579.58.