When Wal-Mart Stores Inc. (NYSE: WMT) forecast earnings per share (EPS) at the end of the second quarter, it noted that its estimate of $4.40 to $4.70 included a negative impact of $0.24 per share related to its pledge to raise wages. The mega-retailer raised wages to $9 an hour in April and plans to raise that to $10 an hour in February of next year.

Wednesday morning the company warned that fiscal year 2017 EPS will decline by 6% to 12%, and the stock took its worst one-day beating in years on the report. And the ripples are still forming: four ETFs have taken big hits, and there is some concern that the promised wage increases might have to be shelved.

Fellow DJIA component McDonald’s Corp. (NYSE: MCD) raised wages in April for the 90,000 or so workers at its company owned stores to $9.90 an hour and has said it will increase that to more than $10 an hour by the end of 2016. But if the impact on earnings promises to shave 5% or so off the total, can either Wal-Mart or McDonald’s resist the pressure from shareholders to delay the pay hikes, or to forego them altogether?

In its statement Wednesday, Wal-Mart said it expects an impact of $1.5 billion on operating income in fiscal year 2017 related to the promised wage hike to $10 an hour. The company’s operating income in its most recent fiscal year totaled $27.15 billion. Wal-Mart also said Wednesday morning that sales are expected to rise 3% to 4% a year, adding $45 to $60 billion to the top line over the next three years.

Combined with CEO Doug McMillon’s statement that “Our investments in our people, our stores and our digital capabilities and e-commerce business are the right ones,” the company does not appear to be backing away from its promise to raise wages.

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And unlike many other large firms that could attract an activist attacks on behalf of shareholders, Wal-Mart may be immune from such an attack simply because the Walton family holds so much of the outstanding stock. In April the family announced that it would distribute about 6% of its stake in the company to a new family-controlled trust in order to keep its stake at less than 50%. The family apparently prefers de facto control.

While Wal-Mart may not have to worry much about an activist attack, McDonald’s does not have the same luxury. The fast-food giant recently just last week began offering an all-day breakfast menu to boost sales, and the jury’s still out on how successful that will be.

The drive by some labor organizations and some federal legislators and officials to push the minimum wage to $15 an hour could be derailed by Wednesday’s announcement from Wal-Mart. For example, both Senator Bernie Sanders and former Secretary of State Hillary Clinton have supported the higher wage: Sanders as a federal minimum wage for everyone, Clinton for New York fast-food workers.

The argument concerning the impact of a $15 an hour minimum wage on the number of jobs that will be lost rages on, and both sides have their own studies supporting their own view. But judging by the reaction to Wal-Mart’s warning, investors have made their position pretty clear.

Wal-Mart shares traded down more than 10% today and have posted a new 52-week low of $60.14. The 52-week high is $90.97 and shares trade at around $60.28 in the late afternoon.

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