The 225-issue Nikkei Stock Average closed at an 18-year low Tuesday as investors fretted over delays in structural reform and a plunge in U.S. stocks.

The benchmark Nikkei shed 156.33 points, or 1.62 percent, to close at 9,475.60, falling below the postbubble closing low of 9,504.41 logged Sept. 17. It is the lowest closing level since Dec. 15, 1983.

The Tokyo Stock Price Index (TOPIX) of all First Section issues fell 17.24 points, or 1.83 percent, to 926.27, its third postbubble closing low in as many days and its lowest since Feb. 13, 1985.