ROC-of-ROC

What is ROC-of-ROC?

ROC-of-ROC applies rate of change twice: it measures how fast the speed of price movement is itself changing. In the physics analogy, price is position, momentum or ROC is velocity, and ROC-of-ROC is acceleration. The second derivative is positive while momentum builds, crosses zero the moment momentum stops building, and turns negative while momentum decays, which can happen well before price itself stops rising.

The appeal is lead time: in an idealized cycle each derivative turns before the one below it, so acceleration rolls over before momentum, which rolls over before price. The cost is noise, because differencing amplifies the fastest fluctuations in a series and doing it twice compounds that. Practical versions smooth the inputs or the output, and treat the reading as context for trend acceleration and inflection rather than as a standalone trigger.

How traders use it

• As an early deceleration warning: price pressing to new highs while acceleration is already negative shows the thrust behind the move fading, a cue to tighten risk rather than an automatic reversal call.
• As a thrust-quality check at breakouts: strongly positive acceleration on the breakout distinguishes impulsive moves from grinding drifts.
• As an earlier zero-cross trigger: acceleration flips sign around the point where momentum peaks, ahead of momentum's own zero cross, but it fires many false starts, so it is usually smoothed and confirmed by other evidence.