The most expensive musical instrument ever sold is the "Lady Blunt" Stradivarius violin, which was auctioned in 2011 for approximately $15.9 million. Made in 1721 by the renowned luthier Antonio Stradivari, the "Lady Blunt" is one of the best-preserved Stradivarius violins in existence. It is named after Lady Anne Blunt, the granddaughter of the poet Lord Byron.

The high price is attributed to its rarity, historical significance, and the craftsmanship of Stradivari, whose instruments are considered some of the finest ever made.

The auction proceeds went to aid victims of the 2011 Japanese tsunami.