The value of marketable securities, such as stock investments that are traded on a public stock exchange, and decreases to your share of the partnership's debt are both treated as cash distributions.
When the total amount of cash distributed is more than a partner's basis in her partnership interest, the difference in the two amounts is a gain.
If you acquired stock in the same corporation in more than one transaction, you own more than one block of stock in the corporation.
If you receive distributions from the corporation in complete liquidation, you must divide the distribution among the blocks of stock you own in the following proportion: the number of shares in that block over the total number of shares you own.
But for tax purposes, the defining line can make a big difference.
A loss results when the liquidating distribution is less than the partner's basis in the partnership.