Near singular matrix: wrong import of data?

[Momentum]

Hi there, I'm doing a panel data regression with both time- as cross-section fixed effects. However, I get a near singular matrix error and I have the idea that that is because I imported my data wrongly. Simply said, I am measuring the influence of past stock performance on future stock performance, with macroeconomic control variables. Assume that I have three stocks and three months data (obviously, I use much more), my excel file (before importing in eviews) looks like this:

Stock - Month - Past performance - Future performance - Economic Variable
A Jan 3 5 6
B Jan -1 2 6
C Jan 0 1 6
A Feb 9 2 4.5
B Feb 3 8 4.5
C Feb 4 3 4.5
A Mar 6 2 8
B Mar 3 0 8
C Mar 2 9 8

As you can see, the last column is per month the same for every stock, which I think causes the near singular matrix error. Do you think the same? Am I organising my data correctly, or should I do this differently? Thanks a lot!

[startz]

You've correctly identified the problem. But if that's the data you have the issue isn't importing, it's that you can't have the last variable and also use time fixed effects.

[Momentum]

Thanks for your reply! So what would be the solution? How else can I control for time-fixed effects?

[startz]

The last variable will pick up all time fixed effects - so it can't be interpreted as just the "Economic variable" effect. Or you can leave it out and put the time fixed effects back in.