A research scientist formerly employed by hedge fund mogul Robert Mercer dropped a lawsuit that accused his ex-boss — one of the biggest financial backers of President Trump's presidential campaign — of firing him for calling Mercer racist and publicly criticizing his support of Trump.

No reason was provided why David Magerman, who worked at Mercer's Renaissance Technologies LLC for two decades, dropped the suit. A notice of voluntary dismissal was filed in federal court in Philadelphia on Wednesday, two days before Mercer was required to formally respond to the claims.

Magerman claimed in the May lawsuit that he was wrongfully fired after his relationship with Mercer and his powerful family soured. For example, Magerman alleged that Mercer's daughter, Rebekah Mercer, a member of Trump's transition team, called Magerman "pond scum" at a celebrity poker tournament after the dispute had boiled into the open.

Robert Mercer, a major investor in Trump-friendly Breitbart News, advised the president to hire two of the Mercer family's longtime political advisers, Stephen Bannon and Kellyanne Conway.

Magerman claimed Mercer's politics "tainted" the hedge fund, while internal policies that prohibit "politely" speaking out against the company in public are "unfair and untenable."

Randy Mastro, one of Mercer's lawyers from Gibson Dunn & Crutcher LLP, didn't immediately return a call for comment. Renaissance had no comment on the lawsuit when it was filed in May. Magerman's lawyer, Robert Fiebach, also didn't return a call.