Ahead of tomorrow's product launches, AFR reports that Apple has become the most shorted stock in the US. Investors already have about $10 billion USD hedged against the company's future, surpassing recent bets against Tesla and Amazon. The shorts come amid a public complaint that tariffs against China could significantly increase Apple's supply costs. On Wednesday, Apple is set to unveil three new iPhone models, as well as a new version of its Apple Watch. Shares in the company have risen this year amid hopes that the new line could revitalise sales of the iPhone, which have been flat in recent years. However, doubts over its Chinese manufacturing operations have hung over the company.