Las Vegas-based gaming company Pinnacle Entertainment Inc. (NYSE: PNK) will more than double in size now that it agreed to acquire Ameristar Casinos Inc. (Nasdaq: ASCA) for roughly $2.8 billion.

As part of the agreement, Pinnacle will acquire all of the outstanding common shares of Ameristar for $26.50 per share in cash, including debt of $1.9 billion, as of Sept. 30. The offer represents a premium of 45 percent over the average closing price of Ameristar common stock over a period of 90 days, ending Dec. 20.

The transaction has received the unanimous approval of both the Ameristar and Pinnacle boards of directors.

The acquisition of Ameristar’s properties will complement Pinnacle’s existing portfolio by adding eight casino-resorts in several notable gaming markets, including: St. Charles near St. Louis, Mo; Kansas City, Mo; Council Bluffs, Iowa; Black Hawk, Colo.; Vicksburg, Miss.; East Chicago, Ind.; and Jackpot, Nev.