Here's a classic startup story with a twist: you build a world-changing technology, you partner with a tech giant to fund it and power it, and then you have to tell potential investors that your relationship with that giant is one of your biggest problems. That's where OpenAI finds itself as it eyes a public offering.

According to a document from its latest funding round, OpenAI has warned investors that its "heavy dependence" on Microsoft Corp. (MSFT) for "a substantial portion of our financing and compute" could pose a significant business risk. It's the kind of disclosure you make when you're getting your house in order for Wall Street—acknowledging that your most important relationship is also a potential single point of failure.

The Scale of the Reliance

Think about what that means. A "substantial portion" of financing and compute. For a company that just secured $110 billion in funding and is reportedly seeking another $10 billion, that's a lot of eggs in one basket. The company's future performance, it says, depends on its ability to diversify its partnerships beyond Microsoft. It's a delicate dance: you need the partner to grow, but you can't be seen as wholly dependent on them when you're asking the public markets for money.

This isn't OpenAI's only headache, of course. The document also highlighted rising compute costs, potential disruptions in the supply of critical chips, and ongoing litigation as other key risks. It's a preview of the kind of disclosures you'd expect in an S-1 filing, offering a candid look at the challenges behind the AI hype.

Revenue Soars, But So Do Costs

And there is plenty of hype to manage. OpenAI's growth has been nothing short of spectacular. The company has surpassed $25 billion in annualized revenue as of last month, up from $21.4 billion a year earlier. That's the kind of trajectory that gets investors excited.

But here's the other side of the coin: building and running advanced AI models is incredibly expensive. The company is now projecting compute spending of about $600 billion through 2030. Let that number sink in. It's a reminder that in the AI gold rush, the companies selling the shovels—like the chipmakers—might be in an even better position than the miners.

The Competition Heats Up

OpenAI isn't mining alone. The competitive landscape is getting crowded. Rival Alphabet Inc.'s (GOOG) Anthropic, which is also gearing up for an IPO, is reportedly targeting a nearly 180% revenue increase in a single year. That kind of aggressive growth target from a well-funded competitor puts immediate pressure on Sam Altman's firm to keep executing flawlessly. In the race for AI dominance, there's no prize for second place.

A Funding Frenzy

The sheer scale of money flowing into this sector is mind-boggling. In February alone, global startup funding hit $189 billion. A huge chunk of that—83% of all venture capital that month—came from just three mega-deals: OpenAI's $110 billion round, Anthropic's $30 billion, and a $16 billion round for Alphabet's Waymo.

OpenAI's investor list reads like a who's who of tech and finance. Beyond Microsoft, the company has taken money from Amazon.com Inc. (AMZN), Nvidia Corp. (NVDA), and SoftBank Group Corp. (SFTBY). Nvidia's investment is particularly notable. CEO Jensen Huang stated that its $30 billion stake may be the last private investment OpenAI takes before it goes public later this year. When the king of AI chips makes a bet like that, people pay attention.

So, what's the takeaway for investors watching from the sidelines? OpenAI is a powerhouse with incredible growth, but it's entering a new phase. Going public means trading the relative privacy of venture capital for the glaring spotlight of the stock market. Its warning about Microsoft dependency is a signal that it knows the rules of the game are changing. It's no longer just about building the best AI; it's about building a resilient, diversified business around it. The coming IPO will be the ultimate test of whether it can pull that off.