The S&P 500 declined on Monday as President Donald Trump imposed a new 15% across-the-board levy on US imports following the Supreme Court's ruling against his sweeping tariffs. The fresh trade measures, announced in response to the court decision, sent ripples through equity markets as investors grappled with renewed uncertainty around global trade policy.

Nvidia Corp. shares bucked the broader market trend, advancing ahead of its highly anticipated earnings report scheduled for Wednesday. The semiconductor giant's gains provided a rare bright spot in an otherwise cautious trading session, with market participants positioning themselves ahead of what could be a pivotal report for the technology sector. The divergence between Nvidia's performance and the broader market decline highlights the growing importance of individual company earnings in driving market sentiment.

The tariff announcement comes amid an already complex trade environment, with investors weighing the potential economic impact of the new levies against corporate earnings strength. Market volatility is likely to persist as traders assess how these measures might affect supply chains, consumer prices, and corporate profit margins across multiple sectors.