AI Model Release Tracker: Opus 4.8's misalignment rates similar to Claude Mythos Preview | ZDNET
X Innovation Home Innovation Artificial Intelligence AI Model Release Tracker: Opus 4.8's misalignment rates similar to Claude Mythos Preview Not every new model is all it's cracked up to be. Our tracker keeps each release in context with its peers, so you know which models are worth your time. Written by Radhika Rajkumar, Senior EditorSenior Editor May 28, 2026 at 2:11 p.m. PT Elyse Betters Picaro/ZDNETFollow ZDNET: Add us as a preferred source on Google.AI labs are shipping new models nonstop. Besides being better and faster than their predecessors, however, every new model isn't guaranteed to be a major step change, despite how the company's PR may wax poetic about them. Model strengths really emerge in context: Where are competitor models lacking or excelling? Which models have outstanding specialties, and which are just catching up to industry standards? Also: How we test AI at ZDNETOur Model Release Tracker helps you make sense of where models stand relative to each other, and whether they're worth a deeper look. While we don't test every model or model update on this list, we'll always include the key elements you need to know, along with our hands-on expert test, where applicable. We also include an Expert Score for certain models. Curious about how we test AI? Check out this breakdown of our process. Here are some of the biggest model releases of 2026 so far and what to know about them. We'll update this list whenever a notable new model arrives. Claude Opus 4.8 Anthropic | May 28, 2026What it does: Replacing Opus 4.7 starting today (at the same price), Opus 4.8 offers faster thinking modes for one-third the cost of the earlier version, according to Anthropic. Like most of Anthropic's models, 4.8 prioritizes coding abilities, scoring higher than 4.7 on two coding benchmarks but not fully besting OpenAI's GPT 5.5. It also "reaches new highs on our measures of prosocial traits like supporting user autonomy and acting in the user's best interest," the company noted in the release, though definitions for what that means remain murky. Also: Anthropic launches Opus 4.8, with honesty as its killer featureWhy it matters: Anthropic has always prioritized model safety and interpretability, but appears to be further emphasizing that standard with this release. The company said Opus 4.7 had a 92% honesty rate, in addition to being less sycophantic and hallucination-prone overall. The fact that it claims 4.8 shows "substantially" lower rates of misalignment than 4.7 indicates an increasingly high standard for model safety, especially because Anthropic compared 4.8's alignment to that of Mythos Preview. GPT-5.5 Instant OpenAI | May 5, 2026What it does: OpenAI said in its announcement that the lighter version of OpenAI's just-released GPT-5.5 is less verbose than its predecessor, GPT-5.3 Instant. It also touted fewer hallucinations and improved factuality, saying "GPT‑5.5 Instant produced 52.5% fewer hallucinated claims than GPT‑5.3 Instant on high-stakes prompts covering areas like medicine, law, and finance." Also: Anthropic's Mythos is evolving faster than expected, reports AI safety agencyWhy it matters: GPT-5.5 Instant replaces GPT-5.3 as the default model in ChatGPT. Again, while the expectation is that each new AI model gets more efficient, easier to use, and makes up less stuff, a significant improvement in hallucinations for a model most people use for fast queries could mean less misinformation spreading among the masses. That's especially critical given how many people are using ChatGPT for everyday health questions, for example. (Disclosure: Ziff Davis, ZDNET's parent company, filed an April 2025 lawsuit against OpenAI, alleging it infringed Ziff Davis copyrights in training and operating its AI systems.)Nemotron 3 Nano Omni Nvidia | April 28, 2026What it does: The latest in Nvidia's open Nemotron family, this model provides agents with multimodal input. That means they can "perceive and reason across visual, audio, and textual inputs within a single shared perception‑to‑action loop," according to Nvidia, thereby unifying multiple capabilities into a single system. Also: AI is an arms race, and the US wants $9 billion in Nvidia superchips to keep upWhy it matters: Normally, systems of agents need to use separate models for speech, vision, and text, meaning they jump across documents, video, and audio to complete multi-step tasks. That slows down workflows, undermines the context agents gather, and racks up inference costs. Nvidia's approach, if it works, would streamline this process and reduce token use, saving you money. Try it on Hugging Face. GPT-5.5 OpenAI | April 23, 2026 Expert Score: 93/100What it does: ZDNET tester-in-residence David Gewirtz technically gave GPT-5.5 an A- score, but said it "can be reductively described as better and faster than GPT-5.4," which is hopefully the bare-minimum expectation for a new model. Specifically, though, the model got better at agentic coding, clearly identifying concepts, scientific research, and factual accuracy. Also: I put GPT-5.5 through a 10-round test: It scored 93/100, losing points only for exuberanceWhy it matters: While the model itself may not be leaps and bounds ahead of its immediate predecessor, the quick turnaround from 5.4 to 5.4 -- less than two months -- indicates how rapidly agentic coding is accelerating OpenAI's model release cycle. As David Gewirtz breaks down, the company, much like other frontier labs using AI to build AI, is shipping updates at an exponentially increasing rate. ChatGPT Images 2 OpenAI | April 23, 2026 What it does: Soon after sunsetting Sora, its generative video model and social platform, OpenAI somewhat confusingly announced Images 2. ZDNET model tester David Gewirtz got an early look at Images 2 before its release and was impressed. While he didn't give this model a formal Expert Score, he said it's fun, a huge leap, and actually useful for work. Why it matters: OpenAI seemed to be getting out of the more consumer-minded AI product game when it discontinued Sora, having been beaten by Anthropic at securing lucrative enterprise contracts. That OpenAI still came out with Images 2 within that redirection narrative indicates that it sees image generators as relevant enough to enterprise AI -- especially on the heels of Anthropic's Claude Design. Claude Opus 4.7 Anthropic | April 16, 2026 What it does: Arriving relatively quickly after Opus 4.6, this model boasts new highs in honesty, reduced sycophancy and hallucinations. It also appears to have a knack for cybersecurity, as it backs the new Claude Security, released shortly after the model itself -- but no, it's not Mythos, as many suspected. Also: Anthropic's new Claude Security tool scans your codebase for flaws - and helps you decide what to fix firstWhy it matters: Hallucinations and honesty are among the most difficult, hard-to-solve issues plaguing even the best models. For Anthropic to claim such significant gains in those areas is no small feat for an AI lab that takes safety seriously. Claude Mythos (Preview) Anthropic | April 7, 2026 What it does: This is a tough one because Mythos isn't actually available to the public. Anthropic created quite a media storm when it positioned the new general-purpose model as too powerful to release as usual. While the model is apparently a step change from earlier Anthropic models, the company was especially alarmed because of the security threat it posed, stating that "it is strikingly capable at computer security tasks." In response to that, Anthropic spearheaded Project Glasswing, a collaborative effort with several rival AI labs, including Google, Nvidia, and Microsoft, as well as security authorities like Palo Alto Networks, "to help secure the world's most critical software, and to prepare the industry for the practices we all will need to adopt to keep ahead of cyberattackers." Also: Apple, Google, and Microsoft join Anthropic's Project Glasswing to defend world's most critical softwareWhy it matters: If we're to believe Anthropic's guidance that Mythos poses a significant threat to the world's software -- so much so that only a select few partners can access it -- cybersecurity apparatuses as they stand may not be prepared to meet the rapidly evolving frontier of model capabilities. Mythos may not be the only model of its caliber, but simply the first of many to come once other labs achieve similar breakthroughs. For now, just a few weeks into its release, Mythos is helping catch software bugs in droves. GPT-5.4 OpenAI | March 5, 2026 What it does: OpenAI framed this new model, released barely three months after GPT-5.2, as specifically designed for professional work. According to the company's own testing (which should always be taken with a grain of salt until verified by a third party), GPT-5.4 matches or outperforms human professionals 83% of the time. Why it matters: As AI companies focus more on gaining enterprise trust (and contracts) while lauding what agentic AI can do, they need models that can handle complex work-related tasks with minimal risk, delay, or prohibitively high costs. Any model advancement that shows prowess in professional workflows has a better chance of being taken seriously by companies struggling to adopt AI, though nothing guarantees seamless integration. Also: OpenAI's