Those three companies account for nearly 125,000 of the standard shipping containers that have come through affected ports in the past year.

A potential strike by workers at more than 30 seaports from Texas to Maine could wreak supply chain havoc in U.S., impacting food supply, medicine, cars and auto parts.

The week on Wall Street began with some trepidation ahead of a heavy flow of economic data coming in the next few days. On the earnings front, Carnival posted a record third quarter. Profits at the cruise ship operator rose 60 percent from a year ago.