The NASA ETF has rapidly become the world's largest space-themed exchange-traded fund, surpassing the long-standing leader UFO, after attracting $375 million in a single day. Despite its success, the fund's exposure to SpaceX has been diluted from 10.3% to 4.6% due to rapid capital inflows, forcing the fund to invest in other space stocks like Rocket Lab and AST SpaceMobile. This dilution has left investors with less SpaceX exposure than anticipated. The ETF, which charges a 0.87% annual management fee, has seen significant gains from other assets, while SpaceX's contribution remains minimal. As SpaceX prepares for its IPO on June 12, concerns grow over the ETF's valuation mechanism, which could delay reactions to market changes. The upcoming IPO is expected to be the largest in history, with a fundraising target of $40 billion to $80 billion, but investors may face challenges if the stock price fluctuates post-listing.