** Shares of General Motors GM.N rise 4.5% to $48.79 premarket

** Says will increase its quarterly dividend by 25% and undertake a new $6 bln share buyback program

** Expects to repurchase $2 bln of shares by first half of 2025

** Increases quarterly dividend to 15 cents from 12 cents per share, effective next planned dividend in April

** In 2024, stock had risen 48.3%

(Reporting by Aatreyee Dasgupta)

((Aatreyee.Dasgupta@thomsonreuters.com))