04:36 PM EDT, 03/20/2026 (MT Newswires) -- The Standard & Poor's 500 index fell 1.9% this week, marking its fourth weekly loss in a row, as the war in Iran continued.

The S&P 500 ended Friday's session at 6,506.48. The index has lost 5.4% in March and is down 5% for the year to date.

The US-Israel war with Iran neared the three-week mark with no clear end in sight. The US sent more Marines to the Middle East while Iran's new supreme leader said "safety must be taken away" from the country's top enemies. Oil prices have climbed as the Strait of Hormuz remains effectively closed, disrupting energy supplies and triggering inflation concerns.

Data released Wednesday showed US producer prices rose at the fastest pace in seven months in February amid notable spikes in wholesale costs of food and energy, as markets braced for higher inflation due to the Iran war.

Also on Wednesday, the Federal Reserve's Federal Open Market Committee kept its monetary policy steady amid uncertainty around the Middle East conflict. "The implications of developments in the Middle East for the US economy are uncertain," the FOMC said Wednesday.

Most sectors in the S&P 500 fell this week, led by a 5% loss in utilities and declines of 4.5% each in materials and consumer staples. Real estate fell 4%, while health care shed 3% and consumer discretionary lost 2.7%. Technology, industrials, and communication services also declined.

Constellation Energy ( CEG ) was among the top weekly decliners in utilities, falling 6.6%. The company said it is selling a portfolio of PJM generation assets to LS Power Equity Advisors in a deal valued at $5 billion, as part of antitrust commitments related to its acquisition of Calpine.

Mosaic (MOS) had the largest percentage loss of the week in materials, sliding 20%. The fertilizer company is faced with a delay in margin expansion from rising raw material costs due to the conflict in Iran, BofA Securities said in a note. "We are downgrading MOS to neutral from buy as margin expansion in phosphate fertilizers is likely delayed a year," the report said.

In consumer staples, McCormick ( MKC ) shares fell 8.7% as the company said it is engaged in discussions for a potential acquisition of Unilever's (UL) food business. McCormick ( MKC ) said the discussions are ongoing and there is no certainty that a deal will be reached.

Just two sectors rose: Energy climbed 2.8%, and financials eked out a 0.4% increase.

The top gainers in the energy sector included APA Corp. ( APA ) , up 13%, and Baker Hughes ( BKR ) , up 11%. Baker Hughes ( BKR ) said it received a 60-month service award from Petrobras (PBR) to support critical turbomachinery equipment for offshore operations in Brazil and a major refinery.

Next week, earnings reports are expected from companies including GameStop (GME), Core & Main (CNM), PDD Holdings (PDD), Cintas (CTAS), and Carnival (CCL, CUK).

Economic data will include a revised report on Q4 productivity, the February import price index, and a final reading on March consumer sentiment.