In 2025, Mark McQuade took a gamble wholly specific to the AI era. Arcee AI, the startup he founded in 2023, was focusing on post-training—the process by which an existing model is honed for humans. But McQuade saw an opening: Meta had just backed off its push into open-weight models, a vital (and tricky) middle ground in AI. Open-weight models allow companies (and people) to securely run state-of-the-art AI without turning their data over to, say, OpenAI or Anthropic. But if McQuade wanted to f...