Early last year, a private equity billionaire started paying regular visits to the White House.

Joshua Harris, a founder of Apollo Global Management, was advising Trump administration officials on infrastructure policy. During that period, he met on multiple occasions with Jared Kushner, President Trump’s son-in-law and senior adviser, said three people familiar with the meetings. Among other things, the two men discussed a possible White House job for Mr. Harris.

The job never materialized, but in November, Apollo lent $184 million to Mr. Kushner’s family real estate firm, Kushner Companies. The loan was to refinance the mortgage on a Chicago skyscraper.

Even by the standards of Apollo, one of the world’s largest private equity firms, the previously unreported transaction with the Kushners was a big deal: It was triple the size of the average property loan made by Apollo’s real estate lending arm, securities filings show.

It was one of the largest loans Kushner Companies received last year. An even larger loan came from Citigroup, which lent the firm and one of its partners $325 million to help finance a group of office buildings in Brooklyn.