Microsoft has recorded a new high on Wall Street after the arrival of Sam Altman, co-founder and former CEO of OpenAI, the start-up behind ChatGPT. Microsoft rose 1.6% in early trading and is now trading around 1% after the news of Altman’s hiring.

Altman, along with other colleagues, will join Microsoft to lead a new artificial intelligence research team, announced by CEO Satya Nadella on X. The mission continues for OpenAI as Altman and his co-founder Greg Brockman join Microsoft’s AI team. Altman said on X that he is excited to build something new with Microsoft that will be incredible.

Former Twitch boss Emmett Shear also announced his acceptance of the position as interim CEO of OpenAI on X. Shear described the opportunity as “the chance of a lifetime” and said he believes OpenAI is one of the most important companies in existence today. He plans to launch an independent investigation within 30 days to shed light on Sam Altman’s firing and the upheaval within the start-up.

These announcements come after a tumultuous weekend when OpenAI’s board of directors fired Sam Altman following a review process that concluded that he was not always blunt in his communications, impeding his ability to fulfill his responsibilities. The board no longer had confidence in its ability to lead OpenAI.