This market resolves YES if Elon Musk ends up making more money from his purchase of Twitter than he would have by investing the same money in the NASDAQ, counting from when he made the initial offer to buy Twitter on April 14th.

This market will remain open until Elon Musk exits his ownership of Twitter, whether by IPO, acquisition, or otherwise. This market resolves YES if and only if the ratio of the Twitter's valuation at the time of that exit to its valuation in Musk's initial offer ($41.39 billion) is greater than the ratio of the close price of the Nasdaq Composite index (ticker ^IXIC) on the day of the exit to the close price on April 14th (13,351.08).

I'll count it as an exit if Musk sells most of his Twitter holdings, even if he keeps a minority stake. If Twitter goes public again, I'll look to its valuation at the end of its first day of trading.