NEW YORK--A widely watched housing index shows home prices dropping by the sharpest rate ever in the second quarter.

The Standard & Poor's/Case-Shiller U.S. National Home Price Index tumbled a record 15.4% during the quarter.

The monthly indices also clocked in record declines. The 20-city index fell by 15.9% in June compared with a year ago, the largest drop since its inception in 2000. The 10-city index plunged 17%, its biggest decline in its 21-year history.

No city in the Case-Shiller 20-city index saw year-over-year price gains in June, the third straight month that's happened.

However, the rate of home price declines slowed in June from the month before, a possible silver lining, the index creators said.