Momentum has slowed for the second day in a row, but the tendency has been some late buying that produces a strong close. With overseas markets operating on Monday when the U.S. is closed, there may be a little reluctance to add new inventory.

Optical component makers are enjoying the best business conditions they’ve arguably seen since the halcyon days of the dot-com bubble. But the same clearly can’t be said for many of the companies that have traditionally been their biggest clients.