Photographer: Andrew Harrer/Bloomberg via Getty Images

IAC/InterActiveCorp subsidiary Match Group, which includes sites like Match, Tinder and OkCupid, agreed to acquire PlentyofFish Media Inc. in a deal valued at $575 million, continuing IAC Chairman Barry Diller’s online-dating expansion.

PlentyofFish is a Canadian Internet dating service based in Vancouver. The deal is expected to close in the fourth quarter, pending regulatory approvals, New York-based Match Group said in a statement Tuesday.

The move further solidifies Diller’s position as the leader in helping people find love online. Prior to the PlentyofFish acquisition, IAC had more than 20 percent of the Internet dating market, which is expected to total $2.4 billion this year, according to researcher IBISWorld.

“PlentyOfFish’s addition both brings new members into our family of products and deepens the lifetime relationship we have with our users across our portfolio,” Sam Yagan, the chief executive officer of Match Group, said in the statement.

IAC owns almost 50 tailored dating sites for anyone from pet lovers to Italians to senior citizens. Investors can buy a stake in Diller’s Match Group later this year when the company plans an initial public offering of less than 20 percent of the unit’s stock.

IAC shares rose 2.5 percent to $84.59 at the close in New York, putting the stock up 39 percent this year.

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