Kurt Cobain’s guitar from Nirvana’s iconic MTV Unplugged performance sold at auction Saturday for a record $6 million. The previous record was $3.95 million for a Black Stratocaster owned by Pink Floyd’s David Gilmour. Pre-auction bids on the 1959 Martin D-18E, purchased by the Nirvana singer at Los Angeles’ Voltage Guitars and modified for the left-handed Cobain, reached $1 million even bidding officially opened Saturday. The guitar received seven bids total, including the winning bid of $6,010,00, the Julien’s Auctions website stated. The guitar also came with its original hard-shell case that Cobain had adorned with a flyer for the...