While markets obsess over artificial intelligence and fiscal sustainability, AllianceBernstein's Inigo Fraser-Jenkins and Robertas Stancikas turn to "something that is actually forecastable: demographics." In their November 2026 report, Demographics: Going the Way of the Ents?, Fraser-Jenkins argues that "Demographics is sometimes dismissed as too slow-moving to be worthy of financial commentary, but for us it is one of the key attributes of a new investment regime." The slow variable, it turns out, has just sped up.
The Break in the Trend
Aging is old news. What is new, Fraser-Jenkins writes, is that "there has been an abrupt fall in fertility in just the last 15 years," and the drop is steeper in lower-income countries and among less-educated cohorts. The industry, AB included, builds growth assumptions on the UN's 2024 forecasts, yet recent fertility tracks the low scenario rather than the base case. Under that path, every region sees sharp working-age contractions from roughly 2040. DM ex US is already shrinking; EM grows until 2040, then turns sharply negative. Holding output per worker at its 1990 to 2025 average, US GDP growth stalls from 2030 even under the medium scenario (see Display 5).
Where Did the Couples Go?
The mechanism is the surprise. "A key part of this change is not so much a decline in the number of children per couple, but a decline in the number of couples," Fraser-Jenkins observes. Fertility within couples barely moves (Display 8); coupling itself collapses, especially among young adults without a degree. Childlessness has migrated from high-earning women to low-income men: "in Norway, 89% of high-earning men are fathers, but that share falls to 28% for the lowest-earning men." Smartphones, social media and a widening political gap between young men and women are the suspects, though the evidence, he concedes, is circumstantial.
Bismarck's Arithmetic
Germany's first state pension set retirement at 70, roughly the life expectancy of anyone who survived to 50. "Applying the same approach to the US today, the retirement age would be 80 and in France 82." AB's earlier work found that "working for an extra 10 years was the only way for a funded pension system to generate sufficient real return to keep retirement income at a similar level to national median income."
To be fair, health is moving the right way. GLP-1 treatment cut long-term sick leave by more than 17% in a Danish study, and US age-specific dementia prevalence fell by nearly two thirds between 1984 and 2024. Offsetting the low-fertility drag in the US "would require about a 30% increase in participation rates across the age cohorts starting in 2030," consistent with a trend dating to the 1980s. The obstacle is politics: "Asking large parts of the population to work to age 69 or even longer seems like a very hard sell in the current political environment."
A Contrarian Silver Lining
The fiscal squeeze is real; the CBO projects interest costs overtaking Social Security spending as a share of GDP by 2045. Yet Fraser-Jenkins rejects the reflexive pessimism. On the claim that more people is inherently good: "We find this argument, frankly, odd." Instead, "We suggest that declining birth rates to below replacement rates are a good thing for the planet, a more obvious good," albeit too late to curb warming.
From Theme to Portfolio
"The principal conclusions for investors are not a series of 'thematic'-type views but the implications for aggregate returns," he insists. The headline: "Hence, our view of a lower-return world with higher volatility." Second, US working-age growth near zero looks poor in absolute terms, but "relative to Europe, Japan or China, this is a highly favorable outcome." Healthcare trades below its average relative multiple, and its policy risks "are not particularly correlated to other big risks in the market today, e.g. the durability of the AI trade, so it can diversify growth exposure within a portfolio." In senior housing, the 80+ cohort nearly triples between 2020 and 2040, while "today's low construction starts effectively lock in very low supply for the coming years."
Key Takeaways for Advisors and Investors
1. Revisit return assumptions. Plans built on UN base-case growth likely overstate long-run equity returns.
2. Hold the US overweight. Demography still favours the US relative to other regions, despite tighter immigration.
3. Use healthcare as a diversifier. Below-average valuations, pricing power and low correlation to the AI trade.
4. Be selective in senior housing. AB favours smaller senior-housing REITs trading at materially lower valuations.
5. Plan for longer working lives. Clients may need, and be able, to work well past 65.
Footnote:
1 Fraser-Jenkins, Inigo, and Robertas Stancikas. Demographics: Going the Way of the Ents? AllianceBernstein, Nov. 2026, https://www.alliancebernstein.com/content/dam/global/insights/insights-whitepapers/demographic-going-the-way-of-ents.pdf.
