My Aunt inherited stocks in 1975 which later became Verizon. She has Alzheimer's so she cannot help. I need a price for Verizon as of March 7, 1975.

She now has 226 shares of Verizon. Can anyone help me to get a cost basis or starting point going back from this? As far as the old records, imagine a harder with Alzheimer's disease. That avenue is not useful.

Computer share the transfer agent could not help. Thank you very much.