NEW YORK — As the fortunes of many Americans go, so goes Wal-Mart, so goes the economy.

Even as the world’s largest retailer reported an 8.6 percent rise in fourth-quarter profit during the busy holiday shopping season, it offered a weaker forecast for the coming months.

The problem? The poor and middle-class Americans Wal-Mart caters to — and who are big drivers of spending in the U.S. — are struggling with rising gas prices, delayed income tax refunds and higher payroll taxes.

Melanie Burkhardt, a mother of two teenagers who shops at Wal-Mart, is one of those people. Burkhardt, a Waycross, Ga., resident, said she’s been hit with a double whammy: the payroll tax hike, which has cut her household monthly income by $260, and higher gas prices.

“We had to do a flip on our budget,” said Burkhardt, a legal assistant who plans to cut back on her trips to Wal-Mart. “This is money we used for things like going to a movie or splurging at Olive Garden. Not anymore.”

It’s widely known that Americans in the lower income brackets continue to struggle even as higher earners benefit from improved housing and stock markets, but Wal-Mart’s results signal that matters may be getting worse for them.

Wal-Mart is the latest in a string of big-name companies from Burger King to Zale to say that Americans are being squeezed by new challenges.

But since Wal-Mart accounts for nearly 10 percent of nonautomotive retail spending in the U.S., it is a bellwether for the economy.

“Wal-Mart moms are the barometer of the U.S. household,” said Brian Sozzi, chief equities analyst at NBG Productions who follows Wal-Mart. “Right now, they’re afraid of higher taxes and inflation.”

Indeed, while wealthier households have seen their stock portfolios grow, poor and middle-class Americans have struggled to regain their financial footing since the recession ended more than 3½ years ago.

Stocks have roughly doubled since June 2009. Dividends and capital gains from stocks, which disproportionately benefit higher-income Americans, are taxed at lower rates compared with ordinary income

At the same time, while incomes for most Americans have failed to keep pace with inflation since the recession, that’s been particularly true for middle and lower-income people.

Median household income, adjusted for inflation, fell 1.5 percent to $50,054 in 2011 compared with 2010, the latest period for which figures are available, according to the Census Bureau.

That was down 8.1 percent from 2007, just before the recession began. (The median is the point halfway between the highest and lowest levels.)

But lower and middle-income households fared worse. The share of overall income earned by the bottom 80 percent of households shrank in 2011, while the income for the top 20 percent grew.

And in 2012, inflation-adjusted hourly pay barely rose, inching up 0.3 percent.