Been thinking about why so many portfolio managers overlook one of the most critical semiconductor stocks in the world. You'd think with all the AI hype, everyone would be all over it, but here's the thing - most people just buy an S&P 500 ETF and call it a day.

Take the Vanguard S&P 500 ETF. It pulled in over $117 billion last year alone. Massive flows. And yeah, if you own it, you're getting exposure to Nvidia, Microsoft, Alphabet - all the obvious AI plays. But there's a gap in that strategy that's worth examining.

Taiwan Semiconductor Manufacturing, or TSMC, doesn't show up in the S&P 500 because it's based in Taiwan, not the US. That's literally the only reason. The company is the world's largest chip foundry, and honestly, it might be more essential to AI advancement than people realize.

Here's why this matters for semiconductor stocks specifically: TSMC is one of only three companies that can manufacture 3 nanometer chips. Their processes deliver better power efficiency and performance than competitors. When you're building AI accelerators for training and inference, power consumption isn't just a nice-to-have - it's everything. Real estate costs money, electricity costs money, and TSMC's technology optimizes both.

Last quarter, their advanced chip sales climbed 35%. The 5nm and 3nm nodes made up 58% of revenue. That's not some niche business - that's where the growth is happening. Management guided for mid-20% revenue growth, and they're backing it up with $38-42 billion in capex this year. That's a 34% increase from last year.

They're also committing $100 billion to build US manufacturing capacity over the next few years. That tells you something about where they see demand heading.

The valuation caught my attention. TSMC shares ran 90% in 2024, but they've pulled back over 20% from the highs earlier this year. Now trading under 19 times 2025 earnings consensus. That's well below the S&P 500 average and cheaper than most major AI-related semiconductor stocks.

What makes that even interesting is management's confidence. They're reaffirming mid-20% growth guidance while maintaining strong operating margins. Long-term, they expect 20%+ annual revenue growth over five years with margins staying above 53%.

Obviously there are risks. Geopolitical tensions, tariffs, the usual stuff. Trump's tariff situation could ripple through their customer base. And TSMC has to spend big capital ahead of demand to be ready, which creates timing risk.

But here's the reality: TSMC's technological moat is real. They attract the best chip designers - Nvidia, Apple - because nobody else can do what they do. That creates a flywheel. More revenue means more R&D spending, which pushes their technology further ahead. By the time competitors catch up, TSMC's already moved to the next node.

If you're strictly in an S&P 500 index fund, you might want to think about carving out a small position in TSMC. By market cap, it would represent about 1.8% of the index if it were included. At current prices, adding a few shares of this semiconductor stock to balance out your tech exposure makes sense.

The way I see it, if you're serious about AI exposure, overlooking the company that actually manufactures the chips powering that AI is a gap worth fixing.