SpaceX shares have fallen more than 5% today to below $152, not far from the $150 price where shares began trading June 12, the day of the rocket maker's initial public offering.

SpaceX joined the Nasdaq-100 index today after the stock gained almost 6% last week in anticipation.

"Hedge funds and short term traders were playing the Nasdaq addition," said Jay Hatfield, CEO at Infrastructure Capital Advisors. "Plus the overall Nasdaq is pretty weak too, so it's not helping."

Even if SpaceX stock slips below $150, it would still be more than 10% above its IPO price of $135, but down more than a quarter from a peak of more than $200 reached soon after its public debut.