U.S. stock markets experienced another severe sell-off overnight, with major indices closing sharply lower. The Nasdaq Composite plummeted over 2%, while the S&P 500 dropped 1.51%. Large-cap technology stocks led the decline. According to reports, the U.S. military is deploying three additional warships and approximately 2,500 Marines to the Middle East. Analysts suggest that escalating tensions in the region have heightened concerns about prolonged conflict, causing the CBOE Volatility Index (VIX) to surge over 11%. Additionally, inflation fears driven by energy price shocks have reshaped global interest rate expectations, with markets no longer anticipating Federal Reserve rate cuts this year.

Notably, after market close, former President Donald Trump stated on his social media platform Truth Social that the U.S. is nearing its objectives as it considers scaling back major military operations against Iran. On March 20, U.S. stocks opened lower and continued to decline throughout the session. By the close, the S&P 500 was down 1.51%, and the Nasdaq fell 2.01%, both hitting their lowest levels since September 2025. The Dow Jones Industrial Average declined 0.96%, closing at its lowest point since last October.

Major technology stocks suffered significant losses. NVIDIA and Tesla each fell over 3%, while Google and Meta dropped more than 2%. Microsoft and Amazon declined over 1%, and Apple closed 0.39% lower. The Philadelphia Semiconductor Index fell 2.45%, with Coherent down nearly 8%, Intel dropping 5%, ASML declining over 3%, and Broadcom losing nearly 3%. Memory-related stocks also saw broad declines: SanDisk fell over 8%, Western Digital dropped more than 7%, Seagate Technology declined over 5%, and Micron Technology slid more than 4%.

In related news, citing U.S. media, it was reported that the U.S. military is reinforcing its presence in the Middle East. Concurrently, sources from Iraq's Oil Ministry indicated that the Iraqi government has decided to implement force majeure measures on all oil fields operated by foreign companies. This development pushed international oil prices higher, with Brent crude futures settling at $112.19 per barrel, a 3.26% increase.

Late in the trading session, reports indicated that U.S. Defense Department officials have prepared detailed plans for deploying ground troops to Iran. It remains unclear under what circumstances such authorization might be granted. Ross Mayfield, an investment strategist at Baird, commented, "If this conflict escalates to involve ground troops, we could face several more weeks of rising oil and natural gas prices. Every headline regarding the region's energy infrastructure will be critical to monitor."

Art Hogan, Chief Market Strategist at B. Riley, noted that in the current uncertain environment, a 10% correction in any index would not be unusual. He added that the S&P 500's broader and more diversified composition has helped cushion its decline, but the market is clearly in a highly uncertain period.

Renewed inflation concerns have led markets to price in potential monetary tightening by the Fed. According to the CME FedWatch Tool, there is a 12.4% probability of a 25-basis-point rate hike at the April meeting. Meanwhile, U.S. Treasuries faced heavy selling pressure on March 20, with the 10-year yield jumping near 4.4% before closing at 4.384%. Gennadiy Goldberg, TD Securities' U.S. rates strategy head, stated, "With the Iran conflict escalating and prolonging, the Treasury market is clearly worried about rising inflationary pressures. Markets are no longer pricing in rate cuts for 2026 but are instead considering the possibility of hikes, driving yields significantly higher."

After the market closed, Trump elaborated on his social media platform, stating that the U.S. is close to achieving its goals as it considers de-escalating major military operations against Iran. The objectives include significantly degrading Iran's missile capabilities and launchers, destroying its defense industrial base, neutralizing its naval and air forces including air defense systems, preventing Iran from nearing nuclear capability, and ensuring robust protection for U.S. allies in the Middle East. Trump also suggested that patrol and security responsibilities for the Strait of Hormuz should be assumed by other user nations, with U.S. support provided only if requested and until the Iranian threat is eliminated.

However, tensions appear to be escalating further. Iran's Islamic Revolutionary Guard Corps announced that its navy and air force conducted the 68th wave of "True Promise-4" operations, employing missiles and dozens of attack drones to strike targets in Israel and several U.S. military bases across the Middle East. The statement emphasized that, by order of Iran's Supreme Leader, the Strait of Hormuz is now "completely closed" to the U.S., Israel, and their allies.