Robert Mercer, co-CEO of quantitative hedge fund Renaissance Technologies, has been in the public eye this year because of his backing of Donald Trump. His political activities sparked a feud with an ex-employee who claims he was fired for criticizing the views of his boss. But none of this appears to have distracted or impacted Mercer’s business. Renaissance Technologies, which was founded by its billionaire chairman James Simons in 1982, has seen its assets under management swell amid  strong performance and investor inflows. Renaissance Technologies now oversees $45 billion, a stunning jump from...