Frank and Lorenzo Fertitta, who have grown their Ultimate Fighting Championship into one of the hottest sports assets in the country, are getting ready to score a a huge financial gain with a second family business.

The brothers are set to sell their Fertitta Entertainment management company to Red Rock Resorts, a family-owned casino, for $460 million, according to a regulatory filing on Thursday.

The cash used to pay the brothers will come partially from the expected initial public offering of Las Vegas-based Red Rock, which this year changed its name from Station Casinos.

Frank Fertitta runs the management company and Red Rock, while Lorenzo, a vice-chair of Fertitta Entertainment, is the chief executive of UFC.

Fertitta Entertainment helps design, develop and operate resort and entertainment destinations, often for Red Rock Resorts.

In 2011, it signed a 25-year management agreement for Red Rock’s 21 casinos — 19 of which are in the Las Vegas area.

It is unusual for gaming companies to pay companies owned by the same executives for managing the facilities and arranging common business events, like entertainment, gaming experts told The Post.

While not normal, the arrangement is perfectly legal.

“The terms of the Fertitta Entertainment Acquisition were negotiated … by a special committee of the board of managers of [Red Rock] comprised of Dr. James Nave and Robert Lewis, each of whom was determined to be disinterested in the Fertitta Entertainment Acquisition,” the company said in the SEC filing.

Calls for comment to the Fertitta brothers at Red Rock were not returned.

The Fertitta brothers, each worth $1.6 billion, according to Forbes, will get $113 million apiece once the management firm is sold to their casino business — while their kids will get $159 million.

Company executives will get some of the remainder, according to the filing.

Separately, Red Rock has paid out $7.4 million over the past three years for the use of a corporate jet, according to the SEC filing.

The jet is owned by a Frank Fertitta family trust and Zuffa LLC, the Fertitta family holding company that owns UFC, the filing states.

The Fertitta family has a long history with the casino.

When it teamed with Colony Capital to take Red Rock private in a 2007 highly leveraged buyout, the family collected about $500 million in the sale, according to SEC filings at the time.

The company, however, had a tough time dealing with its pile of debt. In 2009, it filed for Chapter 11 bankruptcy.

Red Rock exited bankruptcy in 2011 — with a unit of Deutsche Bank owning a 25 percent stake.

While the current unsteady markets may not be the best time to bring a company public, Deutsche Bank has the right, beginning in June, to ask to be cashed out of its investment.

Deutsche Bank declined comment.