** Regional lender HomeStreet's HMST.O shares jump 10.1% to $10.24 in premarket trading
** Larger rival Mechanics Bank agrees to acquire HMST in a $300 million all-stock deal, the companies say
** HomeStreet will issue shareholders of privately-held Mechanics 212.5 million shares
** Upon deal close, HMST will be renamed Mechanics Bancorp and remain a publicly traded company
** Deal, expected to close in Q3 2025, will boost Mechanics' market presence with a full West Coast footprint from San Diego to Seattle
** HMST had last year agreed to merge with smaller rival FirstSun Capital Bancorp FSUN.O, but U.S. banking regulators did not sign off on the deal
** J.P. Morgan advised Mechanics while Keefe, Bruyette & Woods advised HMST
** As of last close, HMST stock has lost 78.9% of its value since IPO in 2012
(Reporting by Arasu Kannagi Basil in Bengaluru)
((ArasuKannagi.Basil@thomsonreuters.com;))