The two-year explosion in home prices appears to be cooling a bit. Black Knight says annual appreciation was down in May for the second straight month. But has the damage already been done? The company, in its May Mortgage Monitor , notes that annual price growth retreated from 20.4 percent in April to 19.3 percent in May. That was the largest negative correction in a single month since 2006. That still left prices up 1.5 percent from April to May – nearly twice the average historic acceleration for that month – and a gain of 10.8 percent during the first five months of the year. Black Knight says home price growth is typically 3 to 4 percent over an entire year. The slowdown is nearly universal. Only three of the 100 largest markets, Miami, Omaha, and Grand Rapids, have not braked a bit over the last six months. Price gains in Austin and Boise have decelerated by 12 percentage points, while Stockton (California), Phoenix, and Seattle have dropped back by 5 to