Major U.S. equities indexes moved lower to start February trading after U.S. President Donald Trump declared over the weekend that he will impose tariffs on imports from key trading partners Canada, Mexico, and China. However, stocks bounced off their morning lows as Trump announced that tariffs against Mexico would be delayed for a month.

While international trade relationships dominated the headlines, the new trading week will also bring earnings reports from major names like Amazon (AMZN) and Google parent Alphabet (GOOGL), as well as a stream of labor market data culminating with Friday morning's release of the January jobs report.

The S&P 500 lost 0.8% on Monday. The Dow recovered from steeper losses in the morning to end the session down 0.3%, while weakness in the tech sector weighed on the Nasdaq, which fell 1.2%.

Shares of Moderna (MRNA) tumbled 7.3%, losing the most of any stock in the S&P 500. Monday's decline extended losses posted late last week when Goldman Sachs downgraded the biotech firm's stock to "neutral" from "buy." The downgrade came after the vaccine maker reduced its product revenue guidance for the second time in six months, leading analysts to believe that Moderna has limited visibility into the sales trajectory of its respiratory vaccine business. Goldman's team also predicted that, given elevated operating expenses, Moderna will not break even on a cash basis until 2029, beyond the company's updated 2028 target.

Franklin Resources (BEN) shares fell 6.9%, giving back some of the strong gains posted last week after the investment management firm posted better-than-expected profits for its fiscal first quarter. Despite the strong bottom-line performance, revenue fell short of estimates, and Franklin reported a decline in assets under management (AUM), reflecting an impact from elevated net outflows. Bank of America slightly raised its price target on Franklin Resources shares to account for updated earnings estimates, but analysts maintained their "underperform" rating on the stock.

FedEx (FDX) shares dropped 6.6% after Loop Capital downgraded the shipping company's stock to "hold" from "buy" and lowered its price target. The decreased outlook for the package delivery company came as Loop analysts downgraded the entire U.S. transportation sector following the White House's tariff announcement, noting that the new trade policies could pressure transportation volumes and increase prices.

Tesla (TSLA) shares tumbled 5.2% as investors weighed the implications of Trump's tariff policies. The electric vehicle (EV) maker could see an impact from shifts in the global trade environment and potential retaliatory moves in response to the tariffs, especially given Tesla's exposure to markets in China as well as its close ties to the U.S. presidential administration. A report showing a downturn in registrations for Tesla vehicles in Norway and Sweden during January also raised concerns about perceptions of the brand in Europe.

IDEXX Laboratories (IDXX) shares posted Monday's best performance in the S&P 500, surging 11.1% after the provider of veterinary healthcare products and services reported better-than-expected sales and profits for the fourth quarter. Growing demand for the company's animal testing offerings helped drive the strong performance, especially in the Companion Animal Group (CAG) segment, where IDEXX provides diagnostic tests, lab services, and platforms for managing veterinary practices.

Molina Healthcare (MOH) shares advanced 4.8%. The managed care company is prepared to release its quarterly earnings report after the closing bell on Wednesday. Analysts anticipate that Molina's sales and profits will be significantly higher compared with the year-ago period, noting that the low-income populations served by the company could contribute to the growth.

A slew of investment research analysts lifted their price targets on AbbVie (ABBV) stock following last week's earnings release. The pharmaceutical firm topped fourth-quarter revenue estimates, boosted by sales growth from its anti-inflammation treatments Skyrizi and Rinvoq, and AbbVie increased its long-term sales outlook for the two drugs. AbbVie shares advanced 3.4% on Monday.