Churchill Downs Inc., the publicly traded company that owns a swath of racing and casino assets across the U.S., has reached an agreement to purchase a majority share in a casino northwest of Chicago that is just miles from its Arlington Park racetrack in Arlington Heights, the company announced Wednesday night. The casino, Rivers Casino in the Chicago suburb of Des Plains, had gross receipts of $433.5 million in 2017, according to records of the Illinois Gaming Board, and is owned by a partnership called Midwest Gaming Holdings. Under the terms of a multi-stage, complex deal involving several partners within Midwest, Churchill will acquire at least a 50.1 percent share in the casino, with a cap of spending $500 million on the deal, the companies said. Churchill will use cash for the deal, the company said. Rivers Casino is one of 10 so-called riverboat casinos in Illinois, but it is far and away the most lucrative, according to gambling board records. Its $433.5 million gross receipts dwarfs the gross revenues of the next-largest casino, Elgin Grand Victoria, which had $168.8 million in gross receipts in 2017, according to the gaming board. Total gross receipts from all 10 casinos in Illinois in 2017 was $1.41 billion. Churchill Downs Inc. and other Illinois racetrack owners have long lobbied for legislation that would allow racetracks to operate electronic gambling devices and tables games, but those efforts have been blocked by the state's powerful casino lobby. State legislation requires casinos to be “attached” to waterways. Rivers Casino has a 44,000-square foot gambling floor and operates just over 1,000 slot machines and 52 tables games. Handle on all of its gambling activities was $3.7 billion in 2017, according to the gambling control board. “This property is the crown jewel of Illinois gaming and one of the country’s premier casinos,” said Bill Carstanjen, Churchill’s chief executive, in a release. “This is an amazing opportunity for CDI.” The transaction is subject to a variety of approvals, and it is expected to close in the first quarter of 2019, the companies said. The news of the Rivers acquisition caught horsemen in Illinois by surprise, according to David McCaffrey, the executive director of the Illinois Thoroughbred Horsemen’s Association. Churchill has joined with horsemen in the past to lobby for casino gambling at Arlington, but the acquisition of a casino that has impeded those efforts has created a strong sense of uncertainty about future efforts on that front. “I can make a case for [the acquisition] being very good for racing in Illinois, and I can make a case for it being bad,” McCaffery said. “Right now we’re just in a wait-and-see position." Although Churchill, which is famously guarded about its long-term plans, has not communicated with horsemen yet about their intentions for the track and casino, McCaffery said he hopes that Churchill remains supportive of casino legislation for Arlington. “Would you rather have 150.1 percent of two casinos that are twenty miles apart, or 50.1 percent of one casino?” he said. “The bull case would say, ‘Giddyup, give me two.’ But I can see the bear case as well.” Along with Arlington Park, Churchill owns and operates a handful of racetrack casinos and other standalone casino properties, along with its flagship racetrack in Louisville (the host of the Breeders’ Cup on Friday and Saturday), Fair Grounds in New Orleans, and Calder Race Course in Miami. Calder’s racing operations are currently being leased to a competitor, The Stronach Group, which operates it as Gulfstream Park West, and the track is expected to cease racing operations after 2020. Churchill announced the transaction on the same day that its board approved a 3-for-1 stock split and a new $300 million stock repurchase outlay. The share repurchase program replaces a previous commitment to use $250 million to repurchase stock, an outlay approved in 2017 that still had $78.3 million remaining unused. Churchill Downs’s board approved two enormous stock buybacks in 2015 and 2017, both to acquire shares held by the Duchossois family, the former owner of Arlington Park until it merged with Churchill in 2000. Those two transactions, which were reached privately, resulted in Churchill paying the Duchossois family nearly $300 million in cash for two million shares. Churchill said that the stock split will give each existing shareholder as of Jan. 11, 2019, two additional shares of stock for each one held. The shares will be distributed as of Jan. 25, and the new share price will be reflected on markets beginning Jan. 28. Churchill also announced its third-quarter earnings Wednesday night, reporting net income of $56.3 million on revenues of $221.3 million. Net income was up substantially from the previous year’s third-quarter figure of $16.7 million, but the vast bulk of that increase was made up of a tax gain on a swap of equity in casinos in New York and Colorado for a casino in Maryland and a reduced tax bill due to the cut in federal corporate tax rates passed earlier this year. While net revenue from the company’s racing operations was flat during the quarter compared to the third quarter of 2017, revenue from Twinspires.com, the company’s market-leading account-wagering operation, was up $6 million, from $66.1 million to $72.1 million, though expenses for the unit were up $6.4 million, to $49.2 million, according to the company’s financial statements. The company’s casino segment had a net revenue gain of $17.5 million, from $87.5 million to $105 million, partly as a result of the equity swaps in the casinos. Casino expenses rose $11.5 million.