** Shares of London-based Marex Group MRX.O down 2.6% premarket at $37.11 after secondary offering prices

** MRX early Thurs announces ~10.3 mln shares at $35.50 for total deal size of ~$365 mln

** Offering price represents 6.8% discount to stock's last sale on Weds

** Private equity firm JRJ Group, BXR Group and Trilantic Capital Partners are the sellers, taking their respective stakes to 14.1%, 9.9% and 9.2%, per the SEC prospectus filing

** After the bell Mon, MRX launched an 8.5 mln share offering. Early that day, co said it bought UK-based cobalt trader Darton Commodities

** G oldman Sachs, Barclays and Jefferies acting as lead bookrunners for the offering

** Through Weds, MRX shares up 22% YTD giving co ~$2.8 bln market cap

** Marex went public last Apr after ~15.4 mln share IPO priced at $19

(Lance Tupper is a Reuters market analyst. The views expressed are his own)

((lance.tupper@tr.com 1-646-279-6380))