GMM - questions: dummy variables and large Ts

[larchalr14]

I am running regression on bank profitability and different variables.

My question is why won't GMM let me use my dummy variable? Is there a different way I can specify my dummy variable? (whether or not a bank is consider a community bank).

Second, I have 82 banks with 4 years. Is this a large enough sample size and observation size?

Thank you so much for your help. I've been looking all over the internet and in books for the answer.

[startz]

What does GMM do when you try, i.e. what do you mean by GMM won't let you?

[larchalr14]

It gives me "Near singular matrix" and as soon as I get rid of the dummy variable it runs.

[startz]

Check whether you are in the dummy variable trap.