The stock market's performance in the first half of 2024 has been remarkable, with the S&P 500 delivering a robust 15% total return year-to-date. According to Goldman Sachs, this ranks as the 21st best performance through June since 1900. Historically, years with similar gains at this point have seen positive returns for the remainder of the year 72% of the time, with a median additional gain approaching 9%. Investors have benefited from exceptional risk-adjusted returns, with the S&P 500's 12-month Sharpe ratio exceeding three times its long-term average. This period of smooth ascent has been characterized by minimal volatility, highlighted by the index's ability to go eight sessions without a move of at least half a percent and a June daily decline of just 0.4%.

Despite the CBOE Volatility Index hovering near multi-year lows around 12, actual volatility in the S&P 500 has been even lower, with a realized volatility just above 7 over the past 30 days in VIX terms. However, concerns have arisen regarding the market's concentration in a handful of large-cap stocks driving much of the index's gains. The market-cap-weighted S&P 500 has outperformed its equal-weighted counterpart by more than ten percentage points this year. Without the substantial contribution from stocks like Nvidia, which has added $1.8 trillion in market value since January 1st, the overall market performance would not be as stellar.