OpenAI just broke up with Microsoft

Max

        April 28, 2026

OpenAI just broke up with Microsoft

OpenAI just broke up with Microsoft · TensorMax

Plus: Musk v. Altman jury seated, Anthropic releases vulnerability-hunting Claude, and David Silver's startup raises $1.1B

TensorMax

Daily AI Market Intelligence

Tuesday, April 28, 2026
2:45 PM ET · 2 min read

          By the TensorMax editorial team
           ·  Drawing from 22 sources across the AI industry

Today's top story

model release

Anthropic releases Claude Mythos, an AI model capable of finding and exploiting software vulnerabilities at scale.

More from today

enterprise adoption

US Space Force selects True Anomaly for Golden Dome space-based interceptor prototype development.

partnership

OpenAI ends its exclusive partnership with Microsoft.

regulatory action
$134B

A nine-person jury was seated for the $134 billion trial between OpenAI CEO Sam Altman and Tesla CEO Elon Musk, with opening arguments beginning in California federal court.

funding event
$50B

OpenAI secures up to $50B in investment from Amazon, including a $15B initial investment and $35B contingent on future conditions.

funding event
$1.1B

David Silver's AI startup raises a record $1.1 billion seed round to pursue superintelligence.

regulatory action

A US judge seated a nine-person jury in the Musk v. Altman trial at a federal courthouse in Oakland, California.

Catch up quick

China ordered Meta to unwind its $2.5 billion acquisition of AI startup Manus, forcing the deal's reversal.

OpenAI releases GPT-5.5, a new base model with improved intelligence, coding, and computer use capabilities, priced at $5/$30 per million tokens.

OpenAI closed a $122 billion funding round to secure compute capacity ahead of a planned 2026 IPO.

Elon Musk's $134 billion civil trial against Sam Altman and OpenAI begins in Oakland federal court.

New multi-turn jailbreaking method achieves high success rates against GPT-5-thinking and Claude-Sonnet-4.5, revealing a new 'para-jailbreaking' vulnerability.

A new study testing 9 prompt injection defenses across 20,000+ attacks found that only output filtering in application code prevented leaks, while all model-based defenses failed.

TCS, Infosys, Wipro, and HCL report 'AI deflation' impacting revenue growth in FY2026 earnings.

Xiaomi open-sources MiMo-V2.5-Pro and MiMo-V2.5 under MIT license, featuring 1M-token context and agent/coding focus.

A new arXiv paper by researchers including Alexis Limozin and Torsten Hoefler shows that the standard SFT-then-RL pipeline outperforms mixed-policy methods by up to +22.2 points on math benchmarks after correcting bugs, 

OpenAI sets GPT-5.5 API pricing at $5 per million input tokens and $30 per million output tokens, claiming improved token efficiency offsets the headline price increase.

NVIDIA releases Nemotron 3 Nano Omni, a 30B-A3B hybrid MoE open multimodal model for video, audio, image, and text reasoning.

Energy consulting sector projected to grow 11% to $17.3B in 2026, driven by AI data center power demand.

OpenAI-linked stocks slumped after reports surfaced that the startup missed key performance targets.

Shin-Etsu Chemical withholds annual outlook due to Iran war price disruptions in silicon wafers.

Data center-linked bonds decline following an OpenAI report that has sparked investor concerns about the sector.

Also on the desk

A nine-person jury was seated for the high-stakes Musk v. Altman trial in California, marking the start of the legal battle over OpenAI's founding mission.techmeme.com

A US federal jury is seated for the high-stakes Musk v. Altman trial in Oakland, California, over OpenAI's founding mission and nonprofit-to-for-profit conversion.techmeme.com

David Silver's new venture has raised $1.1B to build an AI that learns without human data.reddit.com

OpenAI and Microsoft amend their agreement to end exclusivity, allowing OpenAI to serve products across any cloud provider while Microsoft remains the primary partner.techmeme.com

Elon Musk and Sam Altman face off in a federal court trial in Oakland, California, over OpenAI's founding mission and governance.techmeme.com

What landed, what bounced.Hit reply with one story from today that landed for you and one that bounced. Two sentences is plenty.
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