Robinhood stock fell about 5% on Thursday. OpenAI said on Wednesday it had not partnered with Robinhood for the stock tokens the trading platform unveiled earlier this week.

On Monday, Robinhood said it would grant 5 euros worth of OpenAI and SpaceX tokens to eligible users in the EU who register to trade stock tokens by July 7.

But in a post on X, OpenAI said it did not endorse the tokens and was not involved in the offering.

In response, a Robinhood spokesperson said the stock token giveaway was a "limited" offer, and enabled by its stake in a special purpose vehicle, without identifying the vehicle.

Stock tokens have stirred excitement as a way to potentially reshape securities investing, but creating tokens tied to private company shares is more challenging due to strict controls over how those shares can be traded.

SpaceX did not immediately respond to a Reuters request for comment.