For months, wholesale price jumps have been outright benign — a sign that milder price increases were in the pipeline for consumers.

The big picture: That changed in January, as producer prices came in hot. One surprising reason: the gangbusters stock market.

Why it matters: After the hotter-than-expected CPI report earlier this week, the PPI data out Friday morning is igniting fears that progress on inflation is stalling.

• But it's worth noting inflation data can be pushed up (or down) by categories that whipsaw for reasons that signal little about inflation's path. That was the case this month, with a component that closely tracks the stock market.

How it works: The "portfolio management" component suggests that investment managers raised prices sharply last month.

• The category alone rose more than 5% in January — the biggest monthly jump since 2021. It's one key reason (though not the only one) why PPI looked so hot.
• But that surge is because portfolio managers charge fees based on assets under management, which have been boosted on the back of the soaring stock market.

Between the lines: That category is one of many used to inform the all-important Personal Consumption Expenditures price index — the inflation gauge targeted by the Fed.

• Economists say the jump seen in Friday's data will help push the January PCE reading higher.

What they're saying: The category suggests "some upside pressure on PCE inflation," economists at Evercore ISI wrote in a note Friday morning.

• It's "historically volatile and the Fed is unlikely to extract any signal in terms of the underlying inflationary pressures," they note.

The intrigue: That component alone could bump up the core PCE index, which excludes food and energy, by almost 0.1%, according to Inflation Insight's Omair Sharif.

The big picture: PPI rose 0.3% in January — the largest increase since last fall. That jump "can be traced" to a big increase in prices on the services side of the economy, the government said.

• Services rose by the most since July 2023 (goods prices, meanwhile, fell). Besides portfolio management, hospital outpatient care also contributed to that jump.
• Sharif warned about reading too much into the data, posting on X that it was driven by the S&P 500's rise last quarter and new health care contracts.
• "Both of those factors will ease in the next month or two. Not sure this bolsters the 'last mile' story," Sharif added, referring to concerns that the final steps of getting inflation back to the 2% target would be the hardest.