(Reuters) - Investors were nervously awaiting the open of U.S. trading after Wall Street's selloff last week following the Trump administration's tariffs announcement, anticipating another week of turbulence as other nations react.

In the two days following Trump's Wednesday tariff announcement, the benchmark S&P 500 index fell 10.5% and lost about $5 trillion in market value. It was the biggest two-day loss since March 2020. Thursday and Friday's steep slide put the S&P 500 down more than 17% from its February 19 all-time closing high, and brought it closer to bear market territory, which would be a 20% decline.

Futures will open at 1800 ET (2200 GMT) Sunday, which will give an indication of how trading might look on Monday.

"The bull market is dead," said Mark Malek, chief investment officer at Siebert Financial. "We might see some gains in the next few days, but for now they're not going to be sustainable."

The timing of the tariffs news, which coincided with the beginning of the first-quarter earnings season, is contributing to the gloomy outlook, Malek said.

On Sunday morning talk shows, Trump's top economic advisers sought to portray the tariffs as a savvy repositioning. Treasury Secretary Scott Bessent said on NBC News' "Meet the Press" that there was "no reason" to anticipate a recession.

Some traders believe the stock market will at least attempt to stage a comeback of sorts.

"Sometime this week it's probably inevitable that we will have an up day," said Steve Sosnick, chief investment strategist at Interactive Brokers.

The question remains about the sustainability of any rally.

"We may see a day this week where screens are green, but any lasting rally may not arrive for three or four weeks," said Alex Morris, chief investment officer at F/m Investments. "At that point, people will start saying we've taken enough air out of the balloon."