Sep 21, 2026 · 29 min
Momentum investing tests AI-era market herding
Talk Your Book: Price Is the Ultimate Factor
The episode examines whether rules-based momentum can navigate shifting market leadership without pretending to protect investors from broad crashes.
- 1Momentum investing seeks behavioral anomalies while combining quantitative signals with attention to company quality.
- 2AI could make investor behavior more alike, potentially intensifying herding and technology-sector concentration.
- 3Momentum offers relative, not absolute, downside protection and can still fall sharply when markets move together.
Don't miss
Bill Mann clarifies that momentum can rotate away from weakening technology leadership yet still decline sharply during a broad market crisis.
The brief
Bill Mann joins Michael Batnick and Ben Carlson to reframe momentum as a way to capture behavioral anomalies, not simply chase rising prices.
Mann’s Noah principle favors preparing for risks before they become obvious, while quarterly rebalancing helps investors avoid reacting to every short-term move.
The conversation asks whether widely available AI tools will make investors more alike, amplifying herding as technology stocks dominate market leadership.
When leadership shifts toward defensive sectors, momentum portfolios can adapt—but Mann stresses that relative downside protection is not immunity from broad crashes.
Motley Fool Asset Management’s rules-based approach turns the episode’s central lesson into practice: define the rules before fear or excitement takes over.
What was said on this episode
22 statements · 13 positive · 8 negative · 1 neutral
New technology will amplify momentum behavior and accelerate its cycles.
“I do think that the momentum type behavior, which we're talking about today, a lot of momentum strategies, I do think that stuff is going to just get put on steroids and those cycles are going to be happening way, way faster.”
Listen at 1:14
Rules-based investing helps investors maintain a long-term approach.
“that's how you force yourself to be a long-term investor. is you put rules in place”
Listen at 2:21
Momentum tracks behavioral anomalies associated with currently successful market segments.
“what momentum is functionally is. is a way of tracking those behavioral anomalies of what is working in the market.”
Listen at 4:34
Investors should allocate part of portfolios to currently working assets within limits.
“why are you not allocating a component of your portfolio to the things that are working within reason?”
Listen at 5:41
Maintaining exposure to preferred high-quality companies should pay off over time.
“we are invested at all times in the types of companies that we would like to be invested in. And so if you get that right over time, that should pay off.”
Listen at 7:15
Price is the most important investing factor because it incorporates relevant information.
“price is the ultimate factor”
Listen at 9:01
Momentum strategies rely on price being the ultimate investing factor.
“price is the ultimate factor. And a momentum strategy is simply leaning on the fact that that is true.”
Listen at 10:04
Market prices are collectively more informative than individual investor analysis.
“the market is in fact smarter than all of us, regardless of how much sophistication we bring to our analysis.”
Listen at 10:59
People struggle to prepare systematically for future market risks before they become obvious.
“people have a very, very hard time preparing for, in a really principled way, the upcoming flood”
Listen at 12:02
Frequent traders tend to achieve worse investment results.
“people who trade the most tend to do the least well.”
Listen at 16:49
AI models are designed to produce highly consensual answers.
“they are designed and they are meant to give you the highest level of consensus.”
Listen at 18:54
AI models will probably increase investor herding.
“So I think that there probably will be additional hurting.”
Listen at 19:00
Momentum strategies can benefit by detecting changes in market leadership.
“a momentum strategy can actually pay off is by picking up on the real subtle changes in the markets, or even not so subtle.”
Listen at 20:46
Factor models can detect market changes before average investors do.
“it will pick up on what the market is seeing way before the average investor can see it.”
Listen at 21:16
AI-driven economic transformation will create significant disruptions during implementation.
“there are going to be real, real pain points along the way.”
Listen at 23:30
AI disruption will not produce the massive job losses commonly predicted.
“I don't happen to think that it's going to come in the form of the massive job losses that people are talking about.”
Listen at 23:35
Historical technological advances have created more jobs than they destroyed.
“There's never been a technological advancement that has destroyed more jobs than it is created.”
Listen at 23:48
Financial exposure to AI investments will eventually cause substantial disruption.
“the financial exposure that we have to these investments is going to cause a fair amount of disruption at some point”
Listen at 24:05
Unlevered momentum strategies are not designed to avoid losses.
“Our momentum strategies are generally speaking, if they are unlevered, they're not built to not go down.”
Listen at 25:03
Momentum strategies are expected to capture less downside than the overall market.
“The promise of momentum is that it will have a lower downside capture than the overall market.”
Listen at 25:21
A future market crisis will eventually drive correlations toward one.
“at some point it will happen that the markets will, you know, will be in such a crisis that correlations will descend to one”
Listen at 25:41
Momentum strategies will shift toward assets declining least during broad crises.
“The areas that momentum strategies will move into will be the ones that are frankly declining the least, that are showing the most resilience.”
Listen at 25:55
Statements are attributed to the speaker as said on the episode and reflect their view at the time, not PodLume's. They are not advice.