PHILADELPHIA — Racetrack and casino operator Penn National Gaming Inc. said Friday it agreed to be acquired by funds managed by two investment companies for about $6.1 billion in cash.

Penn National shares climbed more than 22 percent in midday trading.

The company, with net revenue of $2.2 billion in 2006, operates 18 gambling facilities stretching from Maine to New Mexico as well as Ontario, Canada.

Its properties include four Hollywood Casinos in Louisiana, Illinois and Mississippi; Argosy casinos in Illinois, Indiana, Missouri and Iowa; and the Boomtown Casino in Biloxi, Miss. It has racetracks, some with slots, in Maine, West Virginia, New Jersey, Pennsylvania, Ohio and New Mexico.

Under the buyout proposal, Penn National shareholders will receive $67 in cash for each share, about a 31 percent premium over the company's closing price of $51.14 on Thursday.

The buyers led by Fortress Investment Group LLC, a publicly traded asset management company, and private equity firm Centerbridge Partners LP will also repay $2.8 billion in Penn National's outstanding debt.

Shares of the Wyomissing, Pa.-based company surged $10.98, or 21 percent, to $62.12 Friday after rising to a 52-week high of $63.68.