SpaceX shares fell 4% in early trading on Friday. The drop came after the company postponed a rocket launch.

This was Starship's 13th test flight. Two Raptor engines failed to start during checks before launch, according to reports.

Elon Musk said on social media the engines will be replaced. He said the next launch attempt is expected early next week.

One report said the new target date is Monday July 20th. SpaceX shares have fallen nearly 23% since joining the Nasdaq-100 stock index.

Some reports say the drop from its highest price could be as much as 35% to 45%. Only about 4% of SpaceX shares can be bought or sold freely.

This makes the stock price swing a lot. Some market watchers say the sharp drop is too strong a reaction to a short delay. The setback adds to recent losses for the space company.