Contrary to popular belief, earnings growth has a very low correlation with decadal stock returns. The primary driver is the change in the valuation multiple (e.g., P/E ratio expansion or contraction). The correlation between 10-year real returns and 10-year valuation changes is a staggering 0.9, while it is tiny for earnings growth.

Most of an index's returns come from a tiny fraction of its component stocks (e.g., 7% of the Russell 3000). The goal of indexing isn't just diversification; it's a strategy to ensure you own the unpredictable "tail-event" winners, like the next Amazon, that are nearly impossible to identify in advance.

The S&P 500's heavy concentration in a few tech giants is not unprecedented. Historically, stock market returns have always clustered around the dominant technology transformation of the time. Before 1980, leaders were spinoffs of Standard Oil, car companies like GM, and General Electric, reflecting the industrial and automotive revolutions.

Over the past two decades, equity analysis has evolved beyond simply valuing a company's physical or financial assets. The modern approach focuses on identifying "alpha" factors—trading baskets of stocks grouped by shared characteristics like strong balance sheets or non-US revenue exposure.

The asymmetrical nature of stock returns, driven by power laws, means a handful of massive winners can more than compensate for numerous losers, even if half your investments fail. This is due to convex compounding, where upside is unlimited but downside is capped at 100%.

Instead of predicting specific companies, identify irreversible macro-trends, or "directional arrows of progress." Examples include the move towards higher energy density (carbohydrates to uranium) or more compact data storage (spinning drives to flash). Investing along these inevitable paths is a powerful strategy.

The goal isn't to know everything about an industry, which has diminishing returns and leads to overconfidence. A better edge comes from efficiently understanding the few critical variables that matter most across multiple opportunities, while consciously ignoring immaterial details.

Contrary to the belief that only a few mega-cap stocks drive market returns, a significant portion of S&P 500 companies—167 in the year of recording—outperform the index. This suggests that beating the market through stock picking is more attainable than commonly portrayed.

Market efficiency increases with company size and liquidity. Therefore, the excess returns (alpha) from investment factors like value are significantly larger in the inefficient micro-cap space. For large-caps, the market is so efficient that factor premiums are minimal, making low-cost indexing a superior strategy.