A secretive $73 billion fund offered staff the rare opportunity to invest - and then delivered a bumper return

Renaissance Technologies, a secretive $73 billion quant fund founded by math whiz James Simons, gave employees the opportunity to increase their stakes in the firm's flagship fund by 50% or more after President Trump's election - if they could do it in three weeks.

At least six employees took out sizable loans in order to do so, Bloomberg News' Miles Weiss reports.

"Many RenTech staffers were caught off guard when told in early December that these limits would be significantly raised for the first time in years," writes Weiss.

With the fresh $2.1 billion injected in January, Renaissance's Medallion fund returned an 11.6% profit in the first half of this year.

While the figure isn't as high as comparable periods from 2015 and 2016 - when the fund saw returns of 18% and 21%, respectively - RenTech is still beating many of the largest hedge funds, including Bridgewater Associates and Two Sigma, which have struggled to post gains this year, Business Insider earlier reported.

Renaissance was founded in 1982 and is known for its secrecy. The company has long held that any cash infusions, like this one, could have a negative effect on returns.

During the second quarter of this year, Renaissance's total assets rose 9.5% to $78.3 billion, regulatory documents filed last week show. During the same period, the S&P 500 - a benchmark for hedge funds - rose just 2.6%.

Read the Bloomberg story here