Leon Black has 750 million reasons to applaud EchoStar’s $2.1 billion acquisition of Hughes Communications.

That’s the estimated profit — $750 million — Black’s Apollo Capital Management stands to pocket from its 57 percent stake in Germantown, Md.-based Hughes — should EchoStar’s deal get the nod from regulators, sources said.

Back in 2004, Apollo affiliate SkyTerra put down about $50 million to acquire a 50 percent stake in Hughes. Since then, Black has added to and sold off pieces of the investment.

A spokeswoman for Apollo declined to comment.

So far, Apollo has given its blessing to the announced tie-up, with analysts and industry observers speculating that it is unlikely that regulators won’t allow the marriage to be consummated.