** Shares of British oil and gas producer Harbour Energy HBR.L down 7.4% at 277 pence
** Stock top loser on the FTSE 250 .FTMC, which is down 0.32%
** BASF BASFn.DE, Harbour Energy's largest shareholder, is selling 80 million shares at 273 pence each, says bookrunner
** Selling price represents a 9% discount to HBR's last close
** BASF's voting rights in Harbour will be about 35% of the total after sale, down from ~40.95%, according to LSEG
** HBR up ~49% this year, as of last close
(Reporting by Megha Kumari)
((Megha.Kumari@thomsonreuters.com;))