It's the case of the vanishing startup: Some of Silicon Valley's most promising names in the fast-developing generative artificial intelligence space are being gobbled up by or tied to the hip of U.S. tech giants.

Short on funds, in the past few months promising companies such as Inflection AI or Adept have seen founders and key executives quietly exit the stage to join the world's dominant tech companies through discrete transactions.

Critics believe these deals are acquisitions in all but name and have been especially designed by Microsoft or Amazon to avoid the attention of competition regulators, which the companies strenuously deny.