Here are links to some of the relevant tax analysis, IRS publications and other resources on asset disposition:

• Ten Important Facts About Capital Gains and Losses.  IRS Tax Tip 2011-35, with links to related documents
• Tax Topic 409, Capital Gains and Losses provides a good overview of capital gains taxes.
• Worthless securities
• IRS Publication 17, Your Federal Income Tax,
•  IRS Publication 544, Sales and Other Dispositions of Assets gives more specific information about capital gains and capital losses
• IRS Publication 551, Basis of Assets
• IRS Publication 550, Investment Income and Expenses (Including Capital Gains and Losses)

Perspectives regarding using capital losses to offset ordinary income:

For a discussion of this question from the AAII Journal, visit http://www.aaii.com/journal/article/capital-pains-rules-for-capital-losses.touch

If you are an individual or partnership that purchased 1244 stock in an IPO, read this http://www.wisegeek.com/what-is-1244-stock.htm and this http://www.law.cornell.edu/uscode/text/26/1244