How do you value a profitless start-up stock? How much is Oklo stock worth? As I just mentioned, Oklo stock is up 15x in value over 12 months, and now costs more than $20 billion. But what about when Oklo stock cost half as much as it did today -- $69 a share? The thing that should worry Oklo investors today: Once Oklo stock stops skyrocketing and investors start questioning the valuation, there's almost no limit to how low this stock could go.