The largest initial public offering ever is just days away, and demand for SpaceX stock is expected to extremely high, with Wall Street clamoring to buy Elon Musk’s rocket and satellite company.

But the flip side of all that buying is plenty of selling as investors need to raise cash for stock purchases by liquidating other shares in their portfolios.

To be sure, IPOs are often accompanied by volatility. But Greg Boutle, head of U.S. equity derivative strategy at BNP Paribas, pointed out in a note Friday that what’s different this time is SpaceX-related volatility will be coupled with the largest market cap ever seen in a U.S. IPO.

SpaceX plans to raise at least $75 billion in its IPO by selling over 555 million shares at $135 a piece, valuing the company at more than $1.75 trillion. If underwriters exercise options for additional allotments to meet high demand, proceeds could grow to $85.7 billion.

The IPO is expected to price Thursday evening, with shares trading Friday on the Nasdaq under the ticker SPCX.