ARIMA options modelling: Does it work?

I have been observing moving average predictions and making some modest efforts of my own in modelling. I cant find any investable idea. Stock prices seem to move following "moods" which are impacted by the morning news. Makes no sense.

(ARIMA models are easy to implement on a spreadsheet. The prediction equation is simply a linear equation that refers to past values of original time series and past values of the errors. Thus, you can set up an ARIMA forecasting spreadsheet by storing the data in column A, the forecasting formula in column B, and the errors (data minus forecasts) in column C. The forecasting formula in a typical cell in column B would simply be a linear expression referring to values in preceding rows of columns A and C, multiplied by the appropriate AR or MA coefficients stored in cells elsewhere on the spreadsheet.)