What happened

Shares of General Motors (GM -1.85%) were moving lower on Tuesday, after news reports and statements from the United Auto Workers (UAW) labor union made it clear to investors that auto factories in the United States won't be reopening soon. 

As of 2:30 p.m. EDT today, GM's shares were down about 5.6% from Monday's closing price.

So what

GM, like most other automakers with factories in North America, shut down its plants in mid-March amid the onset of the coronavirus pandemic. For auto investors worried about the huge loss in revenue that GM and the others are suffering, the big question is: When will those factories reopen?

Officially, GM hasn't given a date, saying only that it's evaluating "week to week." But it's known to be in negotiations with the UAW, along with Ford Motor Company (F -1.93%) and Fiat Chrysler Automobiles (FCAU), trying to pull together a workable plan to restart production while protecting workers. 

Chevrolet Silverado pickup trucks on the assembly line at GM's Flint Assembly Plant in Flint, Michigan, last year.

GM's factories in North America have been shut down since mid-March. Image source: General Motors.

Last Friday, UAW president Rory Gamble drew a line in the sand: Any plan to reopen, he wrote, must allow workers who feel sick to self-quarantine without losing pay. 

The three companies haven't responded to that statement, at least in public. Investors shouldn't read too much into that: The traditional Detroit practice is that the automakers stay quiet during negotiations with the UAW, until the sides come to an agreement.

But it seems clear that there are some spirited discussions going on behind closed doors.

Now what

For all of its bluster, and notwithstanding its strike against GM last year, the UAW has good day-to-day working relationships with all three automakers. It's likely that they'll come to a deal fairly soon, but that deal may involve expensive accommodations for workers and limits on production volumes, at least for a while.

Here's the takeaway for investors: I think there's a good chance that some U.S. auto factories will restart sometime in May, or at least before the end of June. But it will be a slow, step-by-step process, and it may be many months before things are back to where they were before the COVID-19 outbreak.