That month, Jackson visited a US Army post in Japan, Camp Zama, to greet over 3,000 troops and their families. In September 2007, Jackson was still working on his next album, which he never completed. In 2008, Jackson and Sony released "Thriller 25" to mark the album's 25th anniversary. Two remixes were released as singles: "The Girl Is Mine 2008" (with will.i.am), based on a demo version without Paul McCartney, and "Wanna Be Startin' Somethin' 2008" with Akon. For Jackson's 50th birthday, Sony BMG released a series of greatest hits albums titled "King of Pop". Different versions were released in various countries, based on polls of local fans. In 2008, Fortress Investments threatened to foreclose on Neverland Ranch, which Jackson had used as collateral for his loans. Fortress sold Jackson's debts to Colony Capital LLC. In November, Jackson transferred Neverland Ranch's title to Sycamore Valley Ranch Company LLC, a joint venture between Jackson and Colony Capital LLC. The deal earned him . Jackson arranged to sell a large collection of his memorabilia of more than 1,000 items through Julien's Auction House. On the eve of the first public exhibit, Jackson canceled the action after earning between $200 million to $300 million of initial sales from a series of concerts to be held in London. In March 2009, amid speculation about his finances and health, Jackson announced a series of comeback concerts, This Is It, at a press conference at The O2 Arena. The shows were to be his first major tour since the HIStory World Tour that ended in 1997. Jackson suggested he would retire after the shows. The initial plan was for 10 concerts in London, followed by shows in Paris, New York City and Mumbai. Randy Phillips, president and chief executive of AEG Live, predicted the first 10 dates would earn Jackson £50 million. The London residency was increased to 50 dates after record-breaking ticket sales; over one million were sold in less than two hours. The concerts were to run from July 13, 2009 to March 6, 2010. Jackson rehearsed in Los Angeles in the weeks leading up to the tour under the direction of choreographer Kenny Ortega, whom he worked with during his previous tours. Most rehearsals took place at the Staples Center owned by AEG. On June 25, 2009, less than three weeks before the first "This Is It" show was due to begin in London, with all concerts sold out, Jackson died from a cardiac arrest.