Banc One Corp., the nation's eighth-largest bank holding company, said it agreed to acquire New Orleans-based First Commerce Corp. for about $2.7 billion in stock. The purchase would make Banc One the largest banking company in Louisiana, with a leading position in five of the top six markets in the state, Banc One said. Banc One, based in Columbus, Ohio, already operates in Louisiana as a result of its 1995 acquisition of Baton Rouge-based Premier Bancorp. But the new deal would give Banc One a major presence in New Orleans, where First Commerce is based, plus additional banks elsewhere in Louisiana. Banc One has assets of $140.7 billion and more than 1,200 banking offices in 12 states. First Commerce has $9.3 billion in assets. The deal must be approved by stockholders of both companies and banking regulators. In the deal, First Commerce stockholders, for each share they hold, would receive 1.28 shares of Banc One stock. At Friday's closing price, that would make First Commerce worth $70.64 a share, a premium of 21.5% over its pre-deal price. First Commerce shares soared $8.25 to close at $66.38 on Nasdaq. Banc One shares fell $1.63 to close at $53.56 on the New York Stock Exchange.