The dress worn by Marilyn Monroe as she sang "Happy Birthday Mr President" to John F Kennedy has been sold at auction for $4.8m (£3.9m).
The figure-hugging Jean Louis gown, with 2,500 crystals, was bought by the Ripley's Believe It or Not museum chain, exceeding the $3m guide price.
The company's vice president said it was "most iconic piece of pop culture that there is".
Monroe died from a drug overdose just three months after the performance.
The sultry rendition for President Kennedy's 45th birthday at a 1962 Democratic fundraiser at New York's Madison Square was one of her last public appearances.
President Kennedy was shot dead a year later.
The dress, which the auction house said was so tight she had to be sewn into it, had previously been bought at auction for $1.3m in 1999 by the late business mogul and collector Martin Zweig.
The sum raised is likely to set a new world record for the most expensive dress sold at auction. Marilyn Monroe's billowing white dress from the Seven Year Itch sold for $4.6 million (plus $1m in commission) in 2011.
The largest collection of the screen star's possessions ever offered for auction is being sold by Julien's auction house in Beverly Hills over three days.
Also sold on Thursday was the cocktail dress she wore in "Some Like it Hot", which fetched $450,000.
Many of the 1,000 lots come from the estate of her acting coach, Lee Strasberg, who became a close friend of the actress.
She bequeathed her personal effects and clothing to him in her will.