As if we needed any further proof that the new Duchess of Cambridge has serious fashion clout short prom dresses under 200 , it appears she has now surpassed Michelle Obama in selling power.

Since her engagement to Prince William last year teal cocktail dress uk , everything Catherine wears now sells out in minutes, rivalling only the U.S. First Lady's impact on the industry.

The Reiss Shola 4 she wore to meet Mrs Obama last week was the strongest example to date.

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Selling power: The Duchess of Cambridge (left) sparked a fashion frenzy when she wore this Reiss dress last week - she now rivals the so-called '$3billion woman' Michelle Obama (right) in her ability to shift clothes

As soon as pictures of the Duchess appeared online, the British retailer said they were shifting the $340 garments at a rate of one a minute, and traffic to its website soared by 500 per cent before it crashed.

Since it sold out, versions of the dress have been selling for as much as $1, short casual prom dresses 000 on eBay and traffic to the Reiss website remains boosted by 200 per cent.

It echoes the J Crew frenzy sparked by Mrs Obama - dubbed by financial analysts as the $3billion woman - when she wore the label on the Tonight Show in 2008.

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Fashion bestsellers: Catherine on the day after her wedding in Zara (left) celebrity wedding dresses celebrity wedding dresses, in Belfast in Burberry in March (centre) and announcing her engagement in Issa in November last year (right)

Like Catherine, Mrs Obama likes to mix High Street and designer labels, burgundy flower girl dresses and while the $340 outfit also sold out in record time, her endorsement of J Crew only boosted traffic to the company's website by 64 per cent before it crashed due to demand.

But Catherine's impact on sales of the Shola dress was not a one-hit-wonder. She sparked the same response when she elected to wear Reiss's Nanette dress for her engagement photo.

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Setting a trend: Catherine in her official engagement photo wearing her Reiss Nanette dress, which also sold out within a day

And the £ wholesale plus size wedding dresses wholesale plus size wedding dresses;49.99 blue Zara dress she wore on the day after her wedding also sold out within a day.

Even designer items have benefitted from her magic, most famously the blue Issa dress she wore to announce her engagement.

The £399 dress sold out within hours, and it even spawned several imitations including a £14 version from Peacock and a £16 replica by Tesco.

And Burberry sold out of Catherine's £650 frilled wool trench within a day of her wearing it in March.

Of course there is little exact science in the comparison, and Mrs Obama has had three years to develop a track record, compared with the Duchess, who has only enjoyed her high-profile status for less than a year.

But her impact is certainly significant and only looks set to become more powerful.

Last year Mrs Obama was hailed the '$3billion woman' after a study from the Stern School of Business in New York found that a company's stock rocketed after she was pictured wearing its designs.

Financial analysts discovered that as a result, the U.S. First Lady has boosted the economic value of the brands she chooses to wear by $2.7billion (£1.7billion).

The research, which was published in the Harvard Business Review, showed that brands worn by Mrs Obama rose in value by 2.3 per cent, while the rest of the market dropped by 0.4 per cent.

They estimated that just a single appearance could generate up to $14million for a brand or its stockist.

Stern's Professor David Yermack explained that Mrs Obama's fashion influence was down to a number of factors: 'Her personal interest in fashion, recognised by consumers as authentic; her position as First Lady... and the power of the social Internet and e-commerce.'

He added that her influence far exceeded that of other women in the public eye.

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With the J Crew: Michelle Obama's endorsement of J Crew has generated huge sales. In cardigans from the retailer in April 2009 (left and centre) and in the label's gloves at the Presidential Inauguration (right)

'Even fashion icons such as France’s Carla Bruni-Sarkozy do not [have this kind of effect],' he said. 'Bruni-Sarkozy, like many First Ladies, 0 mainly in one brand: Dior. Obama mixes couture with items anyone can buy at a mall.'

'Consumers flock to the stores, and even if they don’ prom styles prom stylest buy what she wears, they often leave with something else.'

Leah Chernikoff of zoodress.com added: bridal gown online bridal gown online 'It’s helpful that both the Duchess of Cambridge and the First Lady wear high street items that real people can actually afford - though Michelle Obama mixes Alaia and McQueen in with her H&M.

'They’re accessible and that’s why people want to dress like them.'