Technology stocks – a key driver of the stock market’s uptrend to new highs in the last few months – are now among those that are pushing Wall Street down because of growing fears of the coronavirus epidemic.

The S&P 500 Information Technology subsector fell by 9.3% from the end of Thursday’s session, outpacing the 7.3% drop for the broader index. Only the energy sub-sector is performing worse, reflecting a sharp drop in oil prices due to concerns that the coronavirus will slow global economic activity.

Investors poured billions in big tech stocks and other inertial bets last year as the Federal Reserve boosted its risk appetite and fed a rally of more than 30% for the S&P 500. Some big tech stocks continued to rise in price, pushing markets to record even after Concerns about the spread of the contagion in China have increased in recent weeks.

Now, the rise in coronavirus cases outside China has made some investors more willing to part with riskier assets in favor of traditional havens, such as gold and US bonds, which have risen in recent days.

As of Friday, the S&P 500 information technology sub-sector represented nearly 55% of the S&P 500’s total returns in 2020, although the sector generated only 24.3% of the market value of the underlying index, explains Howard Silverblott, senior analyst at S&P Dow Jones Indices.

Only four companies – Microsoft, Apple, Amazon, and Alphabet – represent 46.4% of total returns for 2020 by Friday.

This degree of concentration in a small universe of names has caused some investors to worry that they are overweight and vulnerable to a sudden change in risk appetite. The technology sector estimate has recently been the highest in terms of price relative to profit since 2004.

And while technology stocks tend to outperform general indices in good times, they can also fall further than broader markets when the risk appetite disappears. When the S&P 500 collapsed by nearly 20% of its highest value at the end of 2018, the technology sector experienced a sharp decline of 23% during this period.