Credit Suisse First Boston yesterday cut its investment ratings on a wide range of semiconductor chip industry companies, adding fuel to investor concerns about how long the industry downturn will last.

Credit Suisse said it now expects personal computer shipments to decline this year, revising downward its previous forecast that shipments would be flat. CSFB cut its forecast for PC shipment growth in 2002 to 10 per cent, from 17 per cent.