The National Association of Realtors wants the Federal Trade Commission to block the $3.5 billion merger of Zillow (Z) and Trulia (TRLA), according to an article in the New York Post.

According to a source in the NYP, “People are grumbling about the merger. They are arguing there are only three” so there should not be further consolidation.

The two companies will remain separate entities, though real estate agents will be able to advertise on both sites and gain access to combined tech efforts.

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.

The deal has already struck a cord with some people in the industry.

While most mainstream Wall Street analysts are generally positive on the pending $3.5 billion Zillow acquisition of Trulia, skeptics of both the operational and valuation elements of the companies and the deal continue to raise questions.

Meanwhile, there are companies like Realogy Holdings (RLGY), which is projected to receive a boost in business due to the major acquisition.