Bloomberg reported that shares of Sanyo Special Steel Co dropped by the most in almost 7 years after it said their US auto sales fell by the most since the 1980s.

Sanyo Special sank 14% to close at JPY 470 in Tokyo trading, the largest slump since December 18th 2001. Daido Steel Co, a maker of hardened alloy for car parts, dropped 16% to JPY 446, the biggest decline since September 3rd 2001.

Daido gets about 35% of operating income from selling automobile and industrial parts. Sanyo Special gets about 95% of operating profit from specialty steel. Nippon Steel Corporation is the biggest shareholder in both companies.

Toyota Motor Corporation and its two biggest domestic rivals said that US sales fell by as much as 37% as a credit crisis stifled consumer confidence.

Sanyo Special and Daido led declines that dragged the Topix Iron & Steel sub index down by 8% as compared with the 1.9% drop in the benchmark Nikkei 225 Stock Average.