OpenAI employees have sold about $6.6 billion worth of company shares in one of the biggest private wealth creation events in the artificial intelligence industry, according to a report by The Wall Street Journal.

Must read: Sam Altman's outside bets raise fresh conflict questions as OpenAI nears IPO

The secondary share sale, conducted in October last year, reportedly allowed more than 600 current and former employees to cash out a portion of their holdings. The transaction valued the ChatGPT maker at around $400 billion.

Under the deal, some employees were allowed to sell up to $30 million worth of shares each. Around 75 employees reportedly hit the maximum limit permitted under the transaction.

The report said many employees also moved remaining shares into donor-advised funds, allowing them to support charitable initiatives while receiving tax benefits.

The transaction marks a rare moment in Silicon Valley where employees have generated massive personal wealth before a company’s stock market debut. AI firms such as Anthropic and OpenAI are widely expected to become some of the largest public listings in the technology sector.

Must read: OpenAI plans to shift its focus to coding and enterprise businesses: Report

Many OpenAI employees who joined after the launch of ChatGPT were reportedly able to participate in a share sale for the first time after completing the company’s two-year holding requirement.

The surge in OpenAI’s valuation has significantly increased the value of employee stock grants. According to the report, employees who received shares when the company began issuing equity roughly seven years ago have seen the value of their holdings rise more than 100-fold.

The AI talent war has also driven compensation levels sharply higher across the industry. OpenAI reportedly offers annual compensation packages exceeding $500,000 for some technical roles, alongside substantial stock awards.

Must read: OpenAI calls for 4-day workweek, capital taxes as AI reshapes jobs and wealth

Competition for top AI researchers has intensified across the sector. Meta has also been aggressively investing in AI talent, with reports suggesting select researchers have been offered compensation packages worth hundreds of millions of dollars.

Earlier, OpenAI had reportedly capped employee secondary share sales at $10 million per transaction. The company later increased the limit to $30 million amid strong investor demand for exposure to leading AI startups.