The 30-year-old newspaper, website and mobile app provides comprehensive news, race information and bloodstock data across its formats, turning it into the horseracing industry's "bible".
Exponent's takeover was completed with support from Lloyds Bank's commercial banking strategic debt finance division, which provided senior debt facilities, in the Lloyds team's 23rd deal since the referendum.
The value of the deal was not disclosed.
"We are excited about the prospect of working with Exponent to continue our transformation from a newspaper into a world-class multimedia brand," chief executive of The Racing Post Alan Byrne said.
"Exponent's experience with media businesses will be very helpful in expanding the digital footprint of the brand."
Oliver Bower, partner at Exponent, said: "We are delighted to be investing, alongside the management, in the Racing Post.
"The brand is a market leader and has huge potential in an exciting and growing market. With the support of Lloyds Bank we are looking forward to working with Alan and his team to help the business reach its full potential."