Wall Street has a problem. When big tech stocks like Facebook, Amazon and Apple sneeze, the entire market catches a cold.
Five titans of tech -- Apple, Amazon, Google owner Alphabet, Microsoft and Facebook -- made up nearly a quarter of the market value of the entire S&P 500 as of the end of February.
Facebook, Google and Amazon have fallen sharply because of the possibility of more government regulations on the tech sector. That's dragged down the whole market.
The S&P 500 has fallen 5% in the past two weeks and the Nasdaq has tumbled 6%. Even the Dow, which has Apple, Microsoft, IBM, Cisco and Intel as members, is down more than 3%.
But the market rebounded Thursday, led by solid gains in Facebook, Google and Apple.
Should investors be worried that there's too much tech in the major indexes? Perhaps.
Concentration in one sector is fine when things are humming along nicely. Tech stocks surged last year and continued to do so at the start of 2018 thanks to strong earnings.
But now that tech is under pressure, there are some concerns that it could bring about another major market crash like 2000 -- the last time that the sector made up such a large percentage of the overall market.
Still, many analysts and investment strategists think the negative headlines about Facebook's data privacy issues and President Trump's tough talk regarding Amazon will soon fade and that investors will instead focus on upcoming earnings reports.
Big Tech companies will report first quarter results in April and early May and the numbers are expected to be very good.
Wall Street is forecasting a more than 30% jump in earnings for Facebook from last year for example. Google's earnings are expected to rise more than 20%.
The market also has a way of adjusting so that different companies wind up taking the lead while others falter. To that end, Warren Buffett's Berkshire Hathaway has recently moved ahead of Facebook in market value, bumping Facebook to sixth place.
The rest of the top companies in the S&P 500 are a much more diverse group. JPMorgan Chase, Johnson & Johnson, Exxon Mobil and Bank of America round out the top ten. No tech to be found here.
And the Dow, which weights its components by price instead of market value, isn't particularly tech heavy either.
The top five Dow stocks are Boeing, Goldman Sachs, UnitedHealth, 3M and Home Depot. That should help insulate it from any future problems in the sector.
It's also worth noting that the top tech stocks don't make up nearly as big of a percentage of the global stock market as they have in the past, meaning that a tech slump shouldn't drag down markets in Europe or Asia either.
Roman Kouzmenko, executive director for MSCI Core Equity Research, wrote in a blog post Thursday, that the five biggest techs accounted for just 8% of the MSCI World Index at the end of February.
That's actually the lowest concentration for the market's top five stocks in five decades. There was one point in the mid-1970s when just TWO stocks dominated the market.
"The combined weight of IBM and AT&T alone in 1976 was greater than the weight of all the top five stocks today," Kouzmenko wrote.
In other words, the might of 2018's top techs pale in comparison to Big Blue and Ma Bell in their heydays.