Blog
Ideas, method and updates on portfolio analytics and informed investing.
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Private equity in your 401(k) reports 10% volatility and 0.55 correlation to stocks. Neither number is real.
Private markets are being pitched to retail investors in 2026 as the diversifier public markets can't offer. Their smooth-looking returns aren't lower risk — they're infrequent pricing. The mechanism, with the numbers.
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The dollar lost about 8% in 2025: how much of that did your US ETF return quietly give back?
The dollar had one of its weakest years in decades and the euro gained almost 10% against it. If you hold US stocks or ETFs from Europe, currency moved your return before the market did a single thing — here's the mechanism, not a forecast.
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How many stocks do you actually need to be diversified?
A 2026 survey found individual stocks are now the single biggest slice of most portfolios. The research on how many you need to diversify away single-company risk has moved a lot since the 1960s — and the count alone can still mislead you.
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Long-term US bonds just hit an all-time low: why the 'safe' part of your portfolio can fall harder than stocks
The 10-year Treasury hit 5.2% (highest since 2007), the 30-year hit 5.48% (highest since 2004), and the 20+ Year Treasury ETF (TLT) fell to its lowest level since launching in 2002. What duration is, and why the 'cautious' slice of a portfolio can hide more risk than it looks.
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Momentum just had its best run since the dot-com bubble: which factor is your portfolio betting on without you knowing?
The momentum factor gained 44.4% in Q2 2026, and its internal dispersion is the widest since 1990. What investment factors actually are, and why even 'just owning index funds' doesn't mean you're free of them.
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Emerging markets just beat the S&P 500 by 11 points: is your portfolio too American to notice?
The MSCI Emerging Markets Index is up 16% in 2026 versus roughly 5% for the S&P 500, while most US investors still hold 70-90% of their equities at home. Home bias, explained.
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Gold just broke a 40-year pattern: what correlation says about diversification (not the price chart)
Gold hit fresh record highs in 2026 and UBS is telling investors to add a slice of it. But the number that decides whether it actually diversifies your portfolio isn't the price — it's the correlation, and it just shifted.
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Equal weight isn't equal risk: what risk parity actually does
A 50/50 split by capital can quietly be a 95/5 split by risk. How risk parity equalizes risk contribution instead of dollars — and why a calm VIX doesn't mean calm everywhere in your portfolio.
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Wall Street's most crowded trade ever: what to do when almost everyone shares your view
82% of managers surveyed by BofA in July 2026 called 'long semiconductors/AI' the most crowded trade the survey has ever recorded. What it means to hold a market view nearly everyone else holds too, and how the Black-Litterman model turns a view into a number instead of a yes/no.
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Sequence of returns risk: why the order of your gains and losses can matter more than their average
Two portfolios with the identical average return can end up wildly apart if you're withdrawing along the way. What sequence-of-returns risk is, why Morningstar flags the five years around retirement, and how to look at it instead of guessing.
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Cap-weighted or equal-weighted: the S&P 500 isn't as diversified as its name suggests
An index fund isn't a neutral choice, it's a weighting scheme. Why the Magnificent Seven's ~30% of the S&P 500 and 2026's equal-weight rotation are the same story about concentration.
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The worst day isn't in the average: VaR and CVaR explained
In mid-July 2026 the VIX jumped over 13% in a single session on Strait of Hormuz tensions, but the fear concentrated in chips, not the broad market. Why standard deviation never sees that coming, and what actually separates VaR from CVaR.
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The portfolio that drifted on its own: what rebalancing actually is
Never touch your portfolio and it changes anyway: winners get heavier, losers get lighter. How to measure the drift, calendar vs. threshold, and what Opthest does when you ask it to bring the portfolio back to target.
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Correlation isn't constant: why the 60/40 rule can fail you exactly when you need it
Bonds don't always cushion equity drawdowns: correlation between asset classes shifts over time. How it's measured, and why it matters more than the number of positions.
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The portfolio that returned more isn't the better one: risk-adjusted return
Two portfolios, same gain, but one let you sleep and the other didn't. The Sharpe ratio explains why return alone is a half-truth — and where even it stops telling the truth.
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A thousand futures in one chart: reading a Monte Carlo simulation without fooling yourself
The fan chart doesn't predict the future — it draws its distribution. What the median and percentiles mean, why the numbers shift every run, and what the model leaves out.
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The math of recovery: why a −50% doesn't come back with a +50%
Losses and gains aren't symmetric. The recovery table, volatility drag, and why containing the downside matters more than chasing the upside.
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The diversification that isn't there: how many companies do you really own?
Three ETFs don't make three bets. Overlap, look-through and the effective number of holdings: how to measure a portfolio's real diversification.
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Backtesting: what it can really tell you (and how it can fool you)
Testing a strategy on the past is the most honest way to challenge it — provided you know the four traps: overfitting, survivorship, look-ahead and costs.
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The efficient frontier: what it really tells you (and what it doesn't)
The chart that sums up a portfolio's risk/return trade-off: how to read it, what the optimum point is, and why it isn't a promise about the future.
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