The word on the street is that Zillow (Z) is seeking to acquire rival Trulia (TRLA), although both companies are declining to speak about it, Bloomberg is reporting.

Such a merger would create an online real estate listings giant, in that Zillow and Trulia account for 89% of the online real estate listings when put together.

Both companies' stocks surged on the news of the rumor.

In the battle for dominance in the ever-evolving real estate information and online listings space, Zillow and Trulia have emerged as the big dogs on the block.

Together, Trulia and Zillow’s 84.6 million unique visitors in May 2014 account for twice the number of unique visitors as the next three real estate websites put together, according to the Beyond Syndication 2014 report from Clareity Consulting.

Zillow could value Trulia at as much as $2 billion in a purchase, and an agreement may be announced as soon as next week, said one of the people, who asked not to be identified because the information is private. Talks between the companies are ongoing and may not lead to a deal.

Zillow, with a market value of about $5 billion, is more than three times Trulia’s size of about $1.5 billion, as of yesterday’s close.

The companies help buyers and renters find information on homes, generating revenue by charging realtors to give their listings prominence and by selling advertising. Together Zillow and Trulia had more than 85 million unique visitors in June, accounting for about 89 percent of all traffic to real estate sites, according to data from ComScore.

Last week Zillow acquired  Retsly, a Canada-based real estate software startup that was founded in 2013. 

More recently, Trulia and Zillow both reported record-breaking traffic for June. Zillow has increased its traffic in each of the last five months, topping out at just shy of 83 million in June, which eclipsed May’s total by 1.5 million visitors.

Zillow is continuing to increase its own market share while its real estate search partner Yahoo maintains respectable traffic over 5%. Zillow also just added MSN to its “powered by” search partner list, and MSN has historically maintained around 2% of real estate traffic. Zillow’s network now includes AOL, HGTV’s Front Door, Yahoo and MSN.

Trulia is experiencing traffic growth of nearly 50% year over year and reported a record number of 51 million unique visitors in May. Mobile monthly unique visitors in the first quarter of 2014 increased by 68% the same period last year. remains steady, but pretty flat, even falling slightly when long-term partnerships with AOL and MSN were terminated.