Semi Stocks Boost The S&P 500

Since the March 30th low, one of the best performing areas of the stock market has been the semiconductors. At the moment, the Philadelphia Semiconductor Index (or the SOX) has risen for 18 sessions in a row since the March 30th low. Using the tradable VanEck Semiconductor ETF (SMH) as a proxy, the group is now up right around 40% since then, which is a record 18-day rally since its inception.

Of course, the semiconductors are now home to some of the largest stocks in existence.

Broadcom (AVGO) now trades with a greater that $2 trillion market cap and, of course, there is NVIDIA (NVDA), with a market cap above $5 trillion.

Given the S&P 500 is market-cap weighed, the semis are the single largest weight of any industry group. In fact, the group accounts for 15.5% of S&P 500 weight.

So with a combination of massive outperformance and a massively large weight, the semiconductors are to thank for 4.9 percentage points of the index's 12.8% rally since March 30th, meaning they've accounted for roughly 40% of the gain.

As shown below, that is more than twice as large of a positive contribution as the next best, Media & Entertainment, with 2.12 percentage points.

The other two Tech sector industries - Tech Hardware & Equipment and Software & Services - have also made positive contributions. The latter might come as a surprise as it has been a beleaguered group for most of the year. Nonetheless, since the lows, it is to thank for more than a full percentage point of the S&P's 12.8% rally.