New Delhi, July 18 -- SpaceX's blockbuster IPO may have made headlines, but the stock's sharp decline since its listing has made the short sellers the biggest winners in the game. And, currently, they are sitting on about $5 billion in paper profits, according to S3 Partners, a financial markets data provider.

The firm estimated that 192 million SpaceX shares - around 30% of the total float - have been sold short.

Matthew Unterman, a managing director at S3, told Business Insider that bearish investors were doubling down on their short bets against SpaceX, with the notional value of short interest in the company rising to $25 billion from $4.5 billion on June 15.

In fact, Elon Musk's companies have often been targets of short bets.

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