Updates shares, adds analyst comment in paragraphs 4-5, adds graphic

By Shashwat Chauhan and Jaspreet Singh

June 18 (Reuters) - Shares of SpaceX SPCX.O dropped more than 6% on Thursday, as the post-IPO frenzy that briefly placed Elon Musk's rockets-to-AI firm among the world's top five most valuable companies appeared to fizzle out.

The stock was last down 6.5% at $178.50, after falling nearly 5% in the last session. It was still more than 30% above its $135 offering price.

If the losses persist, SpaceX's market value of $2.52 trillion would shrink by more than $150 billion on Thursday.

"Given the magnitude of the IPO and the strong initial performance, some degree of profit-taking is not surprising," IPOX Schuster analyst Kat Liu said.

"This has been a particularly eventful and shortened trading week for the largest IPO in history," she added.

Shares of other U.S. space companies were also down. Rocket Lab RKLB.O and Planet Labs PL.N dropped around 3%, while AST SpaceMobile ASTS.O and Intuitive Machines LUNR.O declined around 7% and 3%, respectively.

Retail investors bought up SpaceX shares aggressively for the last three sessions, with a total net purchase of over $300 million. Activity, however, was muted on Thursday, with only $9.1 million worth of net purchases noted as of 2:00 p.m. ET, according to Vanda Research.

Due to its relatively small public float and high valuation, analysts and portfolio managers have cautioned investors to anticipate volatility early in SpaceX's life as a public company.

SpaceX's valuation surged past $2 trillion following its blockbuster Nasdaq debut last week. Its shares soared in their first two days of trading before giving up some gains as investors assessed whether the company's rich valuation can be justified by its costly AI push.

SpaceX said on Tuesday it would buy Anysphere, the startup behind the popular AI coding agent Cursor, for $60 billion in stocks to boost its presence in the lucrative enterprise AI tools market.

The company's bankers are preparing to meet investors as early as next week to discuss a bond offering of at least $20 billion, a source said on Thursday, as the company seeks funding for its ambitious AI expansion.