OpenAI offers employees the chance to sell $1.5 billion worth of shares to SoftBank in a new tender offer. The new financing will enable SoftBank to increase its stake in OpenAI and allow employees to sell their shares. The deal was driven by SoftBank's Masayoshi Son, who pushed for a larger stake in OpenAI after his $500 million investment in the previous funding round. OpenAI's valuation has surged to $157 billion, fueled by major investments, including $13 billion from Microsoft.