The index of coincident economic indicators fell to 42.9 percent in November -- below the boom-or-bust line of 50 percent for the first time in 19 months -- the Cabinet Office said Wednesday.

The index, which is a key gauge of the nation's economic activity, was earlier revised down to 70 percent for October from a preliminary 85.7 percent.

A reading above 50 percent is taken as a sign of economic expansion, while a reading below that level is considered a sign of contraction. After the recent downtrend in the stock market, the latest figures could fuel further concern that Japan's economy has lost steam.