June 12 (Reuters) - U.S. space stocks tumbled on Friday as investors rushed to lock in gains on the day of SpaceX's market debut, snapping a months-long rally fueled by anticipation over the blockbuster IPO.

The Elon Musk-led company SPCX.O jumped 28%, clinching a valuation of over $2 trillion as both institutional investors and retail traders piled onto the world's biggest stock market listing.

That frenetic buzz around the IPO has put the spotlight on the once-niche space sector, stoking investor confidence in the potential of satellite communications, space travel and off-planet ventures.

"The space sector has seen a strong run up ... and profit-taking is that lazy sort of excuse of why things have gone down. But I think, inevitably, people would be concerned that the hype can't quite live up to expectations," said Chris Beauchamp, chief market analyst at UK-based broker IG Group.

On Friday, shares of Rocket Lab RKLB.O and Planet Labs PL.N slumped about 8% each, while Intuitive Machines LUNR.O plunged 11%. AST SpaceMobile ASTS.O, a much smaller rival to SpaceX's Starlink satellite business, fell more than 12%.

Aerospace and space travel company Virgin Galactic SPCE.N sank some 28%. The stock, with a ticker similar to SpaceX's 'SPCX', surged more than 20% on Thursday, with some pointing to a boost from investors confusing it with SpaceX.

Space-focused exchange-traded funds Procure Space ETF UFO.O, Ark Space & Defense Innovation ETF ARKX.N and Roundhill Space and Technology ETF MARS.N fell between 1% and 6%.

So far this year, the space stocks are up between 34% and 89%, through last close.

The rally in space stocks' valuations had raised concerns, with some analysts and investors questioning their steep multiples that have mirrored SpaceX's own towering price tag even without the famous "Musk premium".

Rocket Lab, for instance, had a $66 billion market value as of last close, even as the company's annual revenue totaled about $600 million last year.

The slump could also be a sign that investors were rotating out of the stocks to make room for SpaceX in their portfolios.

"This could be a classic case of 'capital recycling' where institutional investors may be trimming positions in smaller pure-play peers to free up the massive liquidity and portfolio allocation needed to anchor the SpaceX juggernaut today," said Talley Léger, chief market strategist of The Wealth Consulting Group, a wealth advisory firm.