U.S. single-family home prices fell in May, falling short of expectations of a slight gain, a closely watched survey said Tuesday.
The S&P/Case Shiller composite index of 20 metropolitan areas declined 0.3 percent in May on a seasonally adjusted basis. A Reuters poll of economists forecast a gain of 0.2 percent.
Nonseasonally adjusted prices rose 1.1 percent in the 20 cities, compared with an expectation of a 1.5 percent rise.
"What I find particularly interesting is that on a seasonally adjusted basis, nationally, home prices are falling only a smidgen—three-tenths of 1 percent—but the way these markets go, that could possibly be a turning point," Robert Shiller told CNBC in an interview on "Squawk on the Street."
With pending home sales and new home sales down, however, "there's some clear evidence of a weakening," he added.