I don't really understand what Ventuals is, but my sense is that it's a prediction market on companies' valuations at IPO, which I think kinda makes it like trading private companies' stocks.

As of this writing, Anthropic's market cap on Ventuals is $711B, while OpenAI's is $834B.

I will say that Anthropic's market cap surpasses OpenAI's at the start of the first 24-hour period during which Anthropic's lowest market cap during that time is higher than OpenAI's highest market cap during that time.

Link to Anthropic on Ventuals; Link to OpenAI on Ventuals

For example, over the last 24 hours, here are the price graphs of Anthropic and OpenAI:

Anthropic's lowest market cap during the period was $678B, while OpenAI's highest was (very briefly) $896B.