Sydney Sweeney just sent this American stock soaring

A US clothing brand has seen its share price surge in a “memestock” frenzy after announcing an advertising campaign featuring actress Sydney Sweeney.

Clothing brand American Eagle Outfitters saw its stock jump as much as 12pc in New York after it announced that the Euphoria and The White Lotus actress would star in a new advertising push. The surge added nearly $228m (£168m) to its market value.

Ms Sweeney will appear in a campaign for its winter denim collection that includes a limited-edition jacket as well as “The Sydney Jean”.

While advertising campaigns can and do influence a company’s performance and Ms Sweeney is one of the most recognisable actresses in the US, analysts said the scale of the share price jump was untethered from reality.

The sharp upswing comes after the retailer gained attention on Reddit’s WallStreetBets, a forum known for fuelling so-called extreme rallies in the share prices of so-called memestocks.

Memestocks are companies where the share price is driven by social media hype and online communities, rather than the company’s fundamental financial performance.

The phenomenon emerged during the pandemic as people turned to trading as a way to entertain themselves during lockdowns.

The term memestock was coined after companies including GameStop and Blackberry saw their share prices surge in 2021 despite little in the way of updates about their underlying performance.

The vertiginous rally triggered the collapse of a hedge fund that had bet against GameStop’s stock and helped inspire the 2023 film Dumb Money starring Paul Dano.

American Eagle’s stock was down almost 50pc so far this year prior to this week’s rally after it pulled its annual forecasts because of tariff uncertainty. The company primarily sources its products from China.

Ross Mayfield, an analyst at Baird Private Wealth Management, said memestocks were a symbol of how stock markets had been “gamblified”.

He said: “It says to me nothing about the level of interest rates or financial conditions. This is retail traders moving individual stocks that are heavily shorted.

“It reflects more the gambling culture permeating financial markets. These are not being bid up because of a good earnings report. It’s because of a Sydney Sweeney ad campaign.”

Ms Sweeney, who has 25.2m followers on Instagram, has fronted campaigns for the likes of Ford, Baskin-Robbins ice cream and luxury fashion brand Miu Miu.

As well as being known for her screen roles, Ms Sweeney has become a prominent figure in popular culture and found herself wrapped up in North American culture wars.