This morning, Standard & Poor’s released the latest update of the Case-Shiller home price index, considered the best measure of national housing prices. The
“„“[I]ndex values are computed as a three-month moving average, and so May prices reflect the average of transactions in March, April, and May. These are also closed sales, with contracts concluded a month or two prior to May. Why is this relevant? Because the price data is based entirely on transactions originated before the government’s housing tax credit expired. Most other housing market variables were also rising before the end of the credit, only to tumble back after its expiration. So the index will likely turn down in the months ahead.”