A key indicator of semiconductor demand dropped.

The U.S. semiconductor industry’s book-to-bill ratio dropped slightly in May, the Semiconductor Industry Assn. announced. The ratio slipped to 1.10, down from 1.17 a month earlier, indicating that manufacturers received $110 worth of new orders from U.S. plants for each $100 worth of silicon chips shipped in the United States during the month. Three months ago the ratio was 1.11, and in May, 1985, it was 0.76. Shipments increased 7.4% to $741.8 million in May, matching the average monthly increase since a January low of $557.9 million. May shipments were 33% above January and 8.7% higher than a year ago.