Performance reviews postponed. Projects are cancelled. Travel authorizations are hard to get. There's widespread early retirement. Mergers and leveraged buyouts occur.
Reorganizations occur frequently.
The farther away your position is from the customer, the more difficult it is to justify its existence when revenues fall. Certain departments or jobs are commonly cherry-picked early for layoffs. Stay ahead of the game. Read what the press is saying about your company and industry. Chances are, your company will too.