Jim Cramer warns investors may be selling Nvidia, Apple, Amazon and Microsoft as excitement builds around a potential $4 trillion valuation for SpaceX.

Jim Cramer warns investors may be selling Nvidia, Apple, Amazon and Microsoft as excitement builds around a potential $4 trillion valuation for SpaceX.

Investors have been warned to be wary of cashing in their shares in order to pile into SpaceX's record-breaking stock market float this week.