Overview
April 2026 has become the densest AI model release window in history. Three frontier labs — OpenAI, Anthropic, and Google DeepMind — launched major new models within weeks of each other.
GPT-5.4: The First Truly Unified Frontier Model
OpenAI released GPT-5.4 on March 5, 2026, establishing itself as the most versatile frontier model.
Key Benchmarks:
| Benchmark | Score | What It Measures |
|---|---|---|
| GDPval | 83.0% | Real-world knowledge work across 44 occupations |
| BigLaw Bench | 91% | Complex transactional legal analysis |
| OSWorld (Computer Use) | 75.0% | Autonomous computer task completion |
| Human expert baseline | 72.4% | — |
GPT-5.4 matches or exceeds human professionals in 83% of comparisons. Available in 5 variants: Standard, Thinking, Pro, Mini, and Nano. Context: 1.05M tokens.
Claude Mythos 5: Too Powerful to Release
Anthropic confirmed Claude Mythos 5 in April 2026 — but with unprecedented caveat: it will not be released publicly.
- 10 trillion parameters (MoE architecture)
- 800B–1.2T active parameters per token
- 15.5 trillion training tokens
- Triggered ASL-4 safety protocol (highest risk tier)
First AI model deemed too capable to deploy. Anthropic’s dedicated cybersecurity cluster can construct complete multi-stage attack chains — but with safety layers preventing real-world exploits.
Gemini 3.1 Pro: Google’s Multimodal Answer
Released February 19, 2026 into preview.
| Benchmark | Score | Notes |
|---|---|---|
| ARC-AGI-2 | 77.1% | Highest of all published models |
| GPQA Diamond | 94.3% | Highest ever reported |
| Humanity’s Last Exam | 44.4% | Beat Claude Opus 4.6 |
Features 1M token context, native multimodal processing (text, image, audio, video).
Head-to-Head Comparison
| Feature | GPT-5.4 | Gemini 3.1 Pro | Claude Mythos 5 |
|---|---|---|---|
| GDPval | 83.0% | — | — |
| ARC-AGI-2 | 73.3% | 77.1% | N/A |
| Public Access | Yes | Yes | No |
| Parameters | MoE | MoE | 10T |