Nobel Prize-winning economist Paul Krugman compared Space Exploration Technologies Corp.’s (SPCX) soaring valuation to the “Trump crypto trade,” arguing that the Elon Musk-led company’s $2.6 trillion market capitalization is being driven more by hype than fundamentals.

Krugman also warned that the biggest winners may be investors who sell before enthusiasm fades.

This comes a day after SpaceX’s market cap soared past Amazon.com Inc.’s (AMZN) and briefly eclipsed Microsoft Corp.’s (MSFT), following a blockbuster Nasdaq debut last week.

SpaceX shares were down more than 3% in Wednesday’s opening trade, while Microsoft shares were down nearly 2%. SPCX was among the top trending tickers on Stocktwits at the time of writing.

Krugman…