By Brandon Sawyer
The global sales of North American semiconductor equipment producers have bounced back from their recessionary lows of mid-2009 to levels not seen since 2007. Bookings represent the value of orders placed, and billings are the amount invoiced for products after shipment. The book-to-bill ratio compares the two values for a given period of time and is a leading indicator of demand for semiconductor products. The three-month average for May 2011, latest available, had $1.6 billion worth of orders placed and $1.7 billion shipped, resulting in a 0.97 book-to-bill ratio as 97 cents worth of orders were received for every dollar of product invoiced. During most of 2010, this ratio hovered well above 1 for the first time since 2006, showing strong demand. In recent months, the book-to-bill ratio has dipped back below 1, indicating a weaker but relatively healthy market with supply just slightly greater than demand.