Consulting research digest — September 2026: AI spending outruns the capacity to absorb it

Consulting research published in September 2026 keeps returning to the same constraint. Corporate AI spending doubled in a year, hyperscaler infrastructure budgets grew roughly fivefold in three years, and consumers began handing product research to AI agents. What has become scarce is the capacity to absorb all of it: agent controls, cost governance, grid headroom, trial design, and a P&L line that proves the return.

This digest covers 16 publicly accessible reports and substantive research articles published from September 1 through September 30, 2026. Each entry gives the firm, the publication date, the report's thesis, the evidence its own pages carry, and the decision question it leaves with executives.

The gap between AI leaders and laggards now runs through measurement. BCG's 2026 Applied AI Index, built on a survey of more than 1,300 CxOs across 20-plus sectors, finds almost half of companies generating value from AI, and companies with both strategic clarity and applied AI capability capturing five times as much value as the rest. Companies that measure AI in the P&L realise 3.6% of revenue in AI value, against 1.2% for companies with no formal measurement. 1

The infrastructure bill needs revenue the market has yet to supply. Bain's Technology Report 2026 puts hyperscaler capital spending at roughly $780 billion in 2026, nearly five times the level of three years earlier. Sustaining about $1.5 trillion of annual AI infrastructure spending to 2031 would require an AI market approaching $6 trillion a year; Bain estimates that consumer and enterprise AI could supply $1.2 trillion to $1.8 trillion, leaving a gap near $4.2 trillion. Closing it would add roughly one percentage point to annual global GDP growth. 2

Agent ambitions are running ahead of the controls built to hold them. BCG finds that 42% of companies expect to grant agents autonomy by 2030, while 5% have the full set of critical controls in place. Deloitte's Finance Trends 2027 reports that 77% of finance leaders are comfortable with agents moving beyond recommendations, and 14% are comfortable with fully autonomous agents on critical decisions; 60% expect AI costs and complexity to rise substantially through 2027. 13

Consumers are still spending, and they are finding products through AI. Bain expects US holiday sales to pass $1 trillion for the first time, growing 4.5%, with nonstore sales up 9%. The share of online shoppers who start product searches on generative AI platforms rose to 24% from 17% a year earlier. Deloitte's 2026 Halloween Survey finds 92% of US households planning to take part, at an average of $285 each. 45

Three patterns recur across the 16 entries.

First, absorption is the binding constraint. BCG places 47% of companies in the emerging stage and 7.5% in the future-built group, and notes that 80% of AI spending now sits outside the enterprise IT budget, where most technology governance lives. Deloitte finds that 96% of organisations are running a cost transformation while 14% captured the full value of their highest-priority initiative. Bain finds 53% of late-stage clinical trials delayed and only 16% of sponsors and CROs redesigning roles and workflows around AI. The pattern is the same in each case: the input arrives, and the organisation cannot yet take it in.

Second, the proof standard has risen. BCG's data shows companies that measure AI in the P&L realising three times the value of those that do not. Deloitte's finance leaders approve 66% of large technology investments through a process that puts measurement first. BCG's payments report shows shareholder returns of 6% against 20% for the S&P 500 over five years, and Bain finds 6% of marketing organisations reporting significant AI performance impact today. The reports are converging on the same demand: name the line of the P&L that moves.

Third, the consumer entry point has moved to AI, and the bill for the buildout is arriving. Bain's holiday forecast puts US holiday sales above $1 trillion with 24% of online shoppers starting their search inside a generative AI platform, and Deloitte's holiday-season spending data shows households buying anyway while price expectations swing. BCG's electricity work shows the physical side of the same shift: residential bills outpacing inflation in 80% of OECD countries since 2010, and data centres accounting for 46% of capacity charges in the largest US power market.

For executives, September's reports point to a short set of questions. Which control has to exist before agents get more autonomy? Which AI cost line is governed, and who owns it? Where does the infrastructure bill land on your cost base, and on your customers' bills? Which decision has already moved to an AI agent, and is your product legible to it?

McKinsey's individual report pages returned access-denied responses throughout this run, so its two entries carry the date and thesis published on McKinsey's own insights page and no data points from the reports themselves. Accenture's insights hub publishes reports without visible publication dates, and the dated pages located this run carried July 2026 and August 2026 dates, so no Accenture report is presented as a September entry. Kearney's insights index publishes dates and is readable, but its individual article pages sit behind a bot challenge and returned no body content. Roland Berger, Oliver Wyman, and Strategy& yielded no September report page with a readable original body and a verifiable publication date.