Oil's drop after U.S.-Iran deal optimism gave Wall Street relief by easing inflation and energy-supply fears.

The fastest way to change the tone of global markets this week was not an earnings report. It was a drop in oil.

A Reuters-syndicated market report said Wall Street rallied and the Dow closed at a record as investors reacted to U.S.-Iran deal optimism and sliding crude prices. The same report said technology led the S&P 500 sectors while energy was the biggest laggard.

That split captures the macro trade. Lower oil reduces pressure on inflation expectations, business costs and household fuel bills. It also lowers the risk that central banks will have to respond to an energy shock with tighter policy.

The relief is not evenly distributed. Airlines, cruise operators and other fuel-sensitive businesses can benefit from cheaper energy, while oil producers and energy-service companies lose some of the risk premium that supported earnings expectations.

Goldman Sachs also lowered oil-price targets after the peace-deal news, according to MarketWatch, reflecting the view that much of the geopolitical premium had already been priced into crude.

The caveat is durability. A framework or tentative agreement does not instantly normalize shipping, insurance, inventories or geopolitical trust. The Strait of Hormuz can move from crisis to relief quickly in market pricing, but physical flows often recover more slowly.

For now, investors are trading the direction of travel. If oil keeps falling without signaling weaker demand, it can give equities a cleaner inflation backdrop. If the deal frays, the same trade can reverse just as quickly.

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