Hi, I worked on an H1 visa in the US for 6 years, and moved back to India after that. Due to the sale of stock grants/dividends etc. (that were received when I was in the US), I continue to have some 'US income' and owe some US tax (federal/state + Soc Security/medicare). In effect, I have paid these taxes over the last couple of years, though I was not working in the US.
I would like to know if this income and consequent Soc security taxes contributes towards the 40 credits I need to benefit from the taxes I have paid until now.

Thanks!

If you are not living in the U.S. and are nonresident in U.S. bank interest and stock sales income is not taxable. Submit W-8BEN to the bank and trader.
You pay SS tax and Medicare tax only on the earned income.

Yes, I agree that bank interest and stock sales income are not taxable in the US. However, sale of stock options (that were received during and as a result of my employment in the US) are considered taxable in the US and sale of such options do show up on a W-2. So I am having 'ordinary income' in some sense and paying correspoding taxes, but am not employed in the US or a resident there in any sense. Will Social Security award credits for the soc sec tax I am paying? Or do they care whether I am actually 'employed' in the US for this year?

You probably will be awarded credit in the Social Security system for the taxes you paid. However, unless you reach the 40 quarter minimum, you will not qualify for Social Security benefits.