Curriculum·R409 Grid, DCA, and Rule-Based Automation·about 33 min
Regime dependence, which is the whole game
By the end of this lesson you can
- →State why a grid has no expectancy independent of regime
- →Show that a backtest on one regime is uninformative about the others
- →Compute the same configuration's result across three regimes and read the spread
- →Name what would have to be true for the configuration to be worth running
Senior · enrolled learners
This lesson opens with The quant quake, week of 6 August 2007, read as a regime change.
- What happened
- During the week of 6 August 2007 a number of high-profile quantitative long/short equity market-neutral funds recorded unprecedented losses. They were hit hard on 7 and 8 August despite relatively little movement in equity and fixed-income markets, and kept losing on 9 August when the S&P 500 fell nearly 3 percent. Khandani and Lo's tentative hypothesis is that the losses began with the rapid unwind of one or more sizable quantitative equity market-neutral portfolios, likely a sudden liquidation by a multi-strategy fund or proprietary desk, whose price impact then triggered other funds' stop-loss and deleveraging policies. They cite the Wall Street Journal's report that Goldman Sachs' Global Equity Opportunities fund lost more than 30 percent of its value that week. On 10 August the moves reversed significantly but not completely, which the authors call consistent with the liquidation hypothesis, and they read the losses as the short-term effect of a forced liquidation rather than a permanent breakdown in the strategies' economic drivers. On that reading, the condition the models required, that nobody large was dumping the same positions at once, stopped holding for three days.
- The decision point
- Those strategies had been built and tested on history, and a test on history can only be right about the history it used. What it cannot contain is the state in which the relationship a strategy depends on temporarily does not hold. A grid depends on one such relationship explicitly, being that the price crosses its levels repeatedly and remains inside its range. That is not a parameter the configuration sets. It is a description of the market the configuration requires, and it is the only thing that determines whether the rule earns anything at all.
What you will be able to answer
- →Why has a grid no independent expectancy?
- →What does a one-regime backtest establish?
- →What is the spread across regimes?
- →What would have to be true to run it?
Orientation and Year One are open: anyone can read them without an account. From Year Two onward the lessons are for enrolled learners, because progress through the later years only means anything if it is tracked against a record.
It is free. We do not sell the list and there is nothing to buy at the end of it.
Sources and review
- https://web.mit.edu/Alo/www/Papers/august07.pdf
- https://www.nber.org/system/files/working_papers/w14465/w14465.pdf
- https://papers.ssrn.com/sol3/papers.cfm?abstract_id=1015987
- https://global-q.org/uploads/1/2/2/6/122679606/houxuezhang2020rfs.pdf
Confidence medium·Volatility low·Reviewed 2026-08-07·Owner unassigned
Contested
R405 uses the quant quake at course level for crowding, being that many funds held similar portfolios in a category whose crowding was not generally appreciated beforehand. This lesson uses the same episode for regime dependence, being that the conditions a validated rule requires can stop holding without the rule changing. The two arguments are related and distinct, and the split is declared. Keep it.
The three-regime comparison carries forward R409-03's stated price paths and R409-01's configuration so the numbers remain checkable across the course. Per R409-L2 the lab requires the learner to run their own configuration against real ranging, rising and falling periods with fees and funding, and to pass by producing a regime in which it loses badly and explaining why.
R405-03 owns the seven sins including regime selection. R405-04 owns sample size. This lesson owns the specific case where the strategy's premise is a market state. Keep the splits.