# Stock Forecast Methods

## The Technical Indicator to Watch Rapid Sell-off

One of the best technical indicators to watch a rapid sell-off is a high-order derivative. In mathematics, the derivative is a measure of how a function changes as its argument (input) changes. In stock investing, the derivative can be used to measure how fast the price of a stock changes for a shortest measured period, for example, in case of EOD, one trading day. The following formula can be used for calculation of the first order derivative:

Δ1 = p2 – p1

where p2 – current day closing price, p1 – previous day closing price

In other words, Δ1 is a speed of changing price. If we apply the same formula to two derivatives – current and previous , we get the second order derivative (or acceleration):

Δ2 = Δ12 – Δ11

where Δ12 – current day first order derivative, Δ11 – previous day first order derivative

We can calculate respectfully the third order derivative Δ3, which can be described as speed of changing acceleration. It can be considered as an indicator of panics in the stock market – the more its absolute value is, the more nervous investors behavior in stock market is.

The chart below shows the result of SP-500 index forecast built by Neural Network (trained by the third order derivative). Forecast horizon is two-week period (May 10-21) after May 6 stock market plunge: The charts have been calculated and plotted by Investment Analyzer Inv-An-4.

© Alex Shmatov. Published with permission of the copyright owner. Further reproduction strictly prohibited without permission.

May 8, 2010 -

## 1 Comment »

1. […] it was reported in the research “The Technical Indicator to Watch Rapid Sell-off“, one of the ways to predict a steep downtrend could be to monitor the speed and acceleration […] Pingback by Creating Model To Predict Stock Market Using Butterfly Effect « Stock Forecast Methods | July 10, 2011 | Reply