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More than half of October's solid gains came from just five technology stocks

  • Technology stocks account for 75 percent of the gain in the S&P 500, according to Standard & Poor's.
  • Without technology, the S&P would only be up about 0.5 percent.
  • Five stocks accounted for 52 percent of the gain in the entire S&P 500 in October.

The S&P 500 is up 2.3 percent this month, the best month since February, but it's a lopsided gain, weighted toward Technology.

Sectors in October

Technology: up 7.6 percent
Materials: up 4.1 percent
Banks: up 1.8 percent
Industrials: up 0.4 percent

Technology is so strong this month that it accounts for 75 percent of the gain in the S&P 500, according to Standard & Poor's. Without tech, the S&P would only be up roughly 0.5 percent.

It's worse than that: Five stocks are responsible for most of the gains.

Big Tech in October

Facebook: up 15.5 percent
Amazon: up 12.5 percent
Apple: up 8.2 percent
Google: up 6.1 percent
Microsoft: up 6 percent

Amazon is a consumer discretionary stock, not a technology stock, but you get the point ... the gains this month are very lopsided.

Those five stocks accounted for 52 percent of the gain in the entire S&P 500.

Think about that: Five stocks (1 percent of the S&P 500) accounted for 52 percent of the gains.

That happens because the S&P 500 is weighted by market capitalization. When the biggest stocks (those with the largest market cap) all have a sudden move up at once, the index rises.

What happens if we look at the S&P 500 and equal weight all of the stocks? A very different picture. There's an ETF for that: The Guggenheim S&P 500 Equal Weight ETF (RSP) is up 1.1 percent for the month.

That is exactly half the gain of the regular S&P 500.

  • Bob Pisani

    A CNBC reporter since 1990, Bob Pisani covers Wall Street from the floor of the New York Stock Exchange.

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