PHOTO: SpaceX founder Elon Musk has just welcomed his sixth child. Picture: Philip Pacheco/AFP Source: AFP

Tesla billionaire Elon Musk has listed two multimillion-dollar properties for sale just days after vowing to sell “almost all physical possessions”.

Colourful billionaire Elon Musk has listed several luxury properties for sale just days after publicly promising to sell most of his belongings.

The Tesla and SpaceX founder took to Twitter on Saturday to declare: “I am selling almost all physical possessions. Will own no house.”

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He followed it up with one “stipulation” regarding one of his properties, which formerly belonged to Charlie And The Chocolate Factory star Gene Wilder.

“Just one stipulation on sale: I own Gene Wilder’s old house. It cannot be torn down or lose any (of) its soul,” Musk tweeted.

When asked why he was taking such a drastic step, Musk issued a one-word reply: “Freedom.”

Shortly before tweeting his unexpected pledge, Musk claimed Tesla stock was too high – and soon after, $US14 billion ($A21.7 billion) was wiped off its market cap.