Current market concentration is unprecedented: The largest 100 companies now reflect ~68% of total US market capitalization, the highest since the 1970s. This percentage has risen +23 points over the last 20 years. At the same time, the S&P 500 excluding the top 100 has fallen -16 percentage points, to ~25%, the lowest in at least 52 years. By comparison, 400 mid-cap stocks now make up ~5% of total market cap, down -4 points over the last 14 years. All while the weight of 600 small-cap stocks has declined to ~2%, near the lowest since the 2000 Dot-Com Bubble. Large cap tech has never been bigger.