James Marsden Hurst 1924—2005

Chapter 4.5 Timing Your Buys With Graphics

Case Gruen Industries (1961)

Chapter 4's guiding case: a nameless stock analysed blind with envelopes alone — buy prediction, target and timing, and the outcome: +62% net in eight weeks.

On this page

Who this entry is for — The book's most convincing experiment: a table of weekly highs and lows of a nameless stock, no fundamentals, no news — and channel analysis extracting a complete operating prediction. Then the real data telling how it went.

Source: J. M. Hurst, The Profit Magic of Stock Transaction Timing, Prentice-Hall, 1970 — Chapter 4, Use This Example as Your Channel Prediction GuideThe Kind of Results You Can Achieve (pp. 71–77, Figs. IV-1/IV-5).


Prerequisites

Envelope construction and the state table — the procedure executed here in full.


The blind experiment

In plain words — Hurst gives you numbers only: each Friday's high and low for a stock called "Z Corp". First he asks what you can make of the raw list (little). Then he plots it (better, still no decisions). Then the envelopes — and everything changes.

The three-act game is built so the reader measures the added value of each step. The bare tabulation says nothing operational; the conventional chart (Fig. IV-1) "adds visibility" but does not answer the questions that count — buy? now? later? short? You do not even know the company's name, its dividends, or what the market is doing.

Original Fig. IV-2 — the first envelope on Z Corp
The original 1970 plate: Fig. IV-2, the first envelope adds visibility.

First envelope (Fig. IV-2): it encloses a component with eight samples of ~5–7 weeks; one 3-week sample is magnitude-duration fluctuation and is discarded; the average of the seven valid ones is 6.0 weeks. Three brief overruns stay outside the bounds — the minimum-width compromise documented point by point. Immediate reading: near-term trend down, ~3 more weeks of decline (the last 6-week cycle is 3 weeks along): no buying now.

Second envelope (Fig. IV-3): a single complete cycle, 19 weeks. And here visibility explodes: the centre line of the outer channel — the sum of everything longer than 19 weeks — has rounded a bottom and points up; the 19-week cycle is ~16 weeks along, hence due to low out in ~3 weeks, together with the 6-week one. "Our interest stirs": no shorting, and a purchase two to three weeks out.


The prediction, in writing

Card — The prediction (Fig. IV-4, channels projected 5 months)

  • Buy, do not short.
  • Entry in ~3 weeks, around 7¼–7½ (projected lower bound of the outer channel).
  • Rise over the following 8–10 weeks toward ~11¼: +55%, ≈330%/yr.
  • Next low (L-4) 19 weeks after the first; the October high past the halfway mark, on the outer channel's uptrend.

Only now do you ask your data source for the name — Gruen Industries — "if you wish, check out the fundamentals; you've got several weeks of waiting anyway".


The outcome

In plain words — Timing and moves "very close to being correct" for five months. Bought at 7¼ in the third week; the 11¼ target arrived in four weeks instead of eight-to-ten; and the envelopes, re-run weekly, warned in advance that the stock would do even better.

The real data (Fig. IV-5) confirm the prediction over five months. And the most instructive part is the management: re-running the analysis each week, as early as the third week after purchase the premature, upside puncture of the inner envelope — then of the outer one too — signalled it was "far too early for a peak of the 19-week cycle": channels re-estimated, target raised to ~12. Close: +62% net in eight weeks — an equivalent compounded yield of ≈2,313% per year.

Original Fig. IV-5 — results versus prediction
The original 1970 plate: Fig. IV-5, results versus prediction — five months later.

Warning — The point of the case is not the 62%: it is that every conclusion was reached knowing nothing of fundamentals, "without even knowing the name of the issue". And the prediction was no oracle: it was an estimate with windows and tolerances, updated at every bar — so much so that its best contribution was correcting itself upward mid-flight.


What descends from this case