Yoox SpA agreed to buy Cie. Financiere Richemont SA’s Net-a-Porter business for stock valued at about 719 million euros ($775 million) to create the world’s biggest online luxury-goods retailer.

The deal will give Richemont a 50 percent stake in Yoox, which will be renamed Yoox Net-a-Porter Group, the Geneva-based owner of the Cartier and Chloe brands said in a statement Tuesday. Yoox’s founder, Federico Marchetti, will be chief executive officer, while Net-A-Porter founder Natalie Massenet will be chairman.

The combined company will have more heft in the market as competition intensifies in Web retailing of luxury goods. Department stores are moving online and online malls such as Amazon.com Inc. are developing dedicated sections. Neiman Marcus Group Ltd. agreed to buy Mytheresa.com in September. For more on the trend, see Retail Reboot: Investors Snatch Up E-Commerce Services.

The transaction is positive for Richemont as the combination will improve profitability “considerably” over the next three years, according to Alessandro Migliorini, an analyst at Mirabaud Securities LLP. “The newly formed venture will have more clout against the tech giants that have been encroaching the luxury arena.”

Yoox rose 8.9 percent to 25.24 euros at 11:04 a.m. in Milan. Based on yesterday’s closing price, a 50 percent stake values Net-a-Porter at about 719 million euros. Richemont fell 1.1 percent to 79.15 Swiss francs, giving the company a market value of about 45.4 billion francs ($46.6 billion).

“Yoox shareholders look to have acquired this asset at relatively good value in the context of online valuations,” Simon Bowler, an analyst at Exane BNP Paribas, wrote in a report today.

Richemont’s voting rights will be limited to 25 percent to ensure Yoox Net-a-Porter’s independence, and the Swiss company also will get two seats on the board. Richemont said it expects a one-time gain of about 317 million euros from the transaction. The company will be prohibited from selling half its stake for three years.

“Today, we open the doors to the world’s biggest luxury fashion store,” Massenet said in a statement from both companies. Massenet, a former fashion journalist and chairman of the British Fashion Council, founded Net-a-Porter in 2000.

The combined businesses had net revenue of 1.3 billion euros last year, and adjusted earnings before interest, tax, depreciation and amortization of about 108 million euros, the companies said.

Yoox Net-a-Porter plans to sell as much as 200 million euros of stock after the transaction to raise funds for expansion and gain new shareholders, said Richemont, which will invest in the offering.

Earlier negotiations between Richemont and Yoox stalled in 2013. Richemont has held talks with banks to discuss options for Net-a-Porter, people familiar with the situation told Bloomberg News in November. These included a sale or an initial public offering of the London-based company, the people said at the time.

“This is a game-changing merger between two pioneering companies that have already radically transformed the marketplace since 2000 and will now shift the industry paradigm once again,” Marchetti said in the statement.

Goldman Sachs Group Inc. advised Yoox while Lazard Ltd. and Nomura Holdings Inc. advised Richemont.

--With assistance from Andrew Roberts in Paris and Thomas Mulier in Geneva.

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