U.S. multifamily rents rose 2% year over year in May, according to Yardi Matrix in its latest national report. That is slower than the annual rate in April (2.5%) and also below the current rate of inflation. The latest report on consumer prices puts inflation at 2.5% over the last 12 months.

In fact, Yardi reports, annual rent growth is at its lowest point since 2011. Though that is a national average, the same holds true for many markets, with large gains in rent no longer being a common theme in the sector.

There are still a few markets on steroids, however. Yardi put Orlando in the top spot nationwide for rental growth in May, with a 5.3% annual gain. Las Vegas was second, up 4.9% for the year, but no other metro markets gained more than 4%.

The report chalks up deceleration of rent growth to pressure from deliveries in most metros.

"That has taken a toll on occupancy rates and growth, even in markets with strong demand," the report reads. "With more than 600,000 units under construction and likely to be completed within two years, deliveries will continue to pressure rents."

As new supply enters the market, occupancies are falling. The report said that the national average occupancy for apartments was 94.9% in April, down 80 basis points from a year earlier.

The impact of new supply will be concentrated in submarkets with the most deliveries, which varies widely by market, and the luxury sector, in which most of the development is taking place.

High-end apartments in places like Seattle, Nashville, Austin and Portland, Oregon — all markets where a lot of supply has come online — are contracting, Yardi said. Year over year in Austin, for example, rents dropped 0.5% in April.

Despite the deceleration in rent growth, individual buildings can still see drastic rent increases at times, and combined with sluggish overall wage growth, the stage has been set in some cities for the sporadic return of rent strikes, the Washington Post reports.

Los Angeles in particular has seen the re-emergence of that kind of renters' action, which was last widely seen in the early 20th century. There is also pressure in some markets, namely cities within California, for rent control.