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Giant companies hold huge weight in the S&P 500. That's no surprise. But did you know most of the S&P 500 sectors are ruled by heavyweights, too? ↑ X NOW PLAYING How To Make
Money In Stocks With IBD – Drafted Due To CAN SLIM Reference A single company accounts for 10% or more of the market value of nine of the 11 S&P 500 sectors. And in four of the sectors,
just one stock soaks up a fifth or more of the value, according to an Investor's Business Daily analysis of data from S&P Global Market Intelligence and MarketSmith. The most
concentrated sectors include communications services with ALPHABET (GOOGL) commanding 32% of market value, consumer discretionary with AMAZON.COM (AMZN) at 46%, energy with 25% in EXXON
MOBIL (XOM) and information technology with APPLE (AAPL) at 22%. Such a top-heavy market shows how massive sector winners keep getting even bigger in the S&P 500. Investors must know the
S&P 500 increasingly hinges on big dominant firms. They'd better deliver. "The talk of the town is on the concern that the S&P 500 is top heavy, and that it is dominated
by a bevy of tech behemoths," said Sam Stovall, market strategist at CFRA. But, "it appears that many sectors — not just tech — are dominated by a handful of heavies." HOW
CONCENTRATED IS THE S&P 500? S&P 500 investors are counting on the winners taking most. Just 40 stocks in the S&P 500 make up 50% of the entire index market value, Stovall says.
Digging even deeper, Stovall found just 10 stocks account for 30% of the S&P 500's index market value. And it's not just tech ruling the S&P 500. True, Microsoft and Apple
both dominate the S&P 500, holding 5.9% weights each. Amazon isn't far behind at 4.9%. But the 10 dominant S&P 500 companies hail from six sectors. Three are in communications
services, three in tech and one each in consumer discretionary, consumer staples, financials and health care. This massive concentration goes back to the 1980s when IBM was essentially the
technology industry. IBM ruled the data center of just about every company — until getting blindsided by the personal computer. To this day, IBM's 6.4% weighting in the S&P 500 in
1985 has never been exceeded. Keep in mind the S&P 500 weights its members based on the value of shares available for trading, or float. Float is associated with market value, but could
be less if the founding family still owns a large block of shares. For instance, only about half of WALMART's (WMT) market value is in the public's hands. LOOKING AT THE S&P
500 SECTOR CONCENTRATION What's the most concentrated S&P 500 sector? Consumer discretionary. Amazon, with a market value north of $1.5 trillion, accounts for 46% of the
sector's market value. Add in No. 2 HOME DEPOT (HD) and more than half the sector's market value is spoken for. That means just 3% of the sector's members control most of its
movement. If you're investing in the sector, you'd better watch how those two are doing. What about tech? It takes four S&P 500 tech stocks, or 6% of the sector's
population, to account for half of the weighting. Conversely, industrials is the least concentrated S&P 500 sector. Its top holding, UNION PACIFIC (UNP), only accounts for 5% of the
sector's market value. It takes nearly a quarter of the sector's stocks to account for half of index value, Stovall says. Keep in mind, though, there are still giants that could
make a splash in the S&P 500. A number of the top big stocks this year aren't in the S&P 500 yet. If TESLA (TSLA) is added to the S&P 500 following its blowout quarterly
profit, it alone would account for nearly 9% of the consumer discretionary sector. Might be time to make some room. MOST S&P 500 SECTORS DOMINATED BY AN INDUSTRY HEAVYWEIGHT SECTOR
BIGGEST WEIGHT SYMBOL SECTOR WEIGHT (BASED ON MARKET VALUE) Communication Services Alphabet (GOOGL) 31.8% Consumer Discretionary Amazon.com (AMZN) 45.9% Consumer Staples Walmart (WMT) 16.9%
Energy Exxon Mobil (XOM) 25.3% Financials Berkshire Hathaway (BRKA) 16.0% Health Care Johnson & Johnson (JNJ) 9.7% Industrials Union Pacific (UNP) 5.3% Information Technology Apple
(AAPL) 22.0% Materials Linde (LIN) 17.7% Real Estate American Tower (AMT) 15.5% Utilities NextEra Energy (NEE) 16.3% SOURCE: IBD, S&P GLOBAL MARKET INTELLIGENCE _Follow Matt Krantz on
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