ARK’s Cathie Wood counters Bill Ackman’s inflation warning

Two of Wall Street’s loudest voices are arguing about the same question: does AI break the Federal Reserve’s playbook? Bill Ackman thinks it might, in a way that fuels inflation. Cathie Wood thinks it might too, just in the opposite direction.

The ARK Invest CEO and CIO pushed back on Ackman’s warning that the Fed’s September rate hike could backfire. Her case rests on two claims: the 10-year Treasury yield sits at its long-run median, and AI inference costs are falling at a pace that makes old inflation fears look dated.

How the argument unfolded

It started on September 25, 2026, when Ackman posted on X about the Fed’s 25 basis point rate increase. He suggested the move may have been a mistake.

Ackman’s concern is that AI spending may not respond to that brake pedal. If demand for AI resources is inelastic, meaning buyers keep paying regardless of cost, higher borrowing costs might not slow it down. In his framing, that could feed a self-perpetuating inflationary spiral.

Wood replied on September 29. She argued that rising interest rates reflect genuine real yields and stronger-than-expected growth, not inflation pressure creeping into the system.

The numbers behind Wood’s case

Wood expanded on her view during ARK’s October “In The Know” session. Her first data point was historical. She said the current 10-year Treasury yield sits at its median dating back to 1790.

Her second point was about technology costs. Wood said AI inference costs have fallen 99.99% annually at constant performance levels.

She tied that cost collapse to demand. Wood pointed to OpenAI’s revenue run rate climbing from $20 billion to $70 billion as evidence that cheaper operations are unlocking much bigger usage.

Wood described the likely outcome as “benign deflation”, the kind where prices fall because things get cheaper to produce, not because demand is collapsing.

Two other data points sit in the backdrop of the debate. US money supply is growing at approximately 5.7%, which has not resulted in higher inflation. And 90% of global data center financing is directed toward the United States.

Why this split matters

Ackman’s camp worries the Fed could raise rates and see little effect on AI spending, leaving inflation intact while other parts of the economy absorb the pain. Wood’s camp believes productivity gains and cost-cutting technology can support sustained growth alongside lower or stable inflation.

What this means for investors

There are clear signals to watch. One is whether AI inference costs keep falling at the rate Wood describes, and whether that shows up in broader price data. Another is whether demand figures like OpenAI’s revenue run rate keep climbing, which would support her claim that cheaper AI drives volume rather than price hikes.

The Fed’s next moves matter too. If policymakers keep tightening and inflation stays contained, Wood’s thesis gains ground. If prices keep rising despite higher rates, Ackman’s concern about an insulated AI sector starts looking less theoretical.

Disclosure: This article was edited by Diego Almada Lopez. For more information on how we create and review content, see our Editorial Policy.