| Tax Basis of Inherited Stock?
The IRS rules state that the basis of inherited stock, generally speaking takes up "the Stepped Up Basis", that is the basis becomes the market value at the time of your Grandmother passed.
It definitely does not take place at the time of GrandFather passing away as the stock passes to Grandmother (tax free) at GrandFathers basis price. But, the passing of Grandmother and the resulting transfer of the stock to the Trust, results in the Basis being "stepped up basis to Fairmarket Value", market price prevailing at time of transfer to the Trust.
Now, there is something called "Alternative Valuation Method" that could have been used when the stock got transferred to the Trust. If the Executor selected the alternative valuation method, a value elected that chooses the stock price after 6 months of Grandmothers passing away, you may be able to acheive a higher stock basis. Please contact the Trustee to determine whether this election was made. If so, you may be able to claim a higher basis, assuming the stock price was valued higher at that time. | 
