Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Cost basis allocation question: GM bonds conversion to stock & warrants
I found additional evidence on TDAmeritrade's website that helps confirm that the 3/17/11 prices Jason found are the ones to use since all three were traded on that day.  Although GM+A had prices and trading as early as 2/28/11, GM+B's price and trading shows up no earlier than 3/14/11, but there was no trading indicated for GM+A on 3/14 so 3/14 can't be used.  The two warrants were not traded every day after they came out. The next date that I found when all three, GM, GM+A and GM+B had trades was 4/11/11.  I found Google and Yahoo Finance unable to produce the historical prices for the warrants that far back.  Unfortunately, you need to be a TDA accountholder in order to access TDA's historical price information for stocks.