Slumping stock prices, a rising yen and higher oil prices dampened the business confidence of major companies in the April-June period, sending the key confidence index to the lowest level in four quarters, according to a government survey released Wednesday.

The index of business conditions at companies capitalized at 1 billion yen or more came to 1.8 on an all-industry basis, down from 6.1 for the previous quarter for the second straight quarter of deterioration, according to the survey of 11,673 firms conducted jointly by the Cabinet Office and the Finance Ministry.

The reading, worse than the 8.3 the companies projected in the January-March survey, was the lowest since the 0.9 marked in the April-June quarter last year.