The Federal Reserve said this week it will no longer buy mortgage backed securities from Fannie Mae and Freddie Mac. Some people worry mortgage rates could rise as a result. Senior Editor Paddy Hirsch explains why.

The Federal Housing Administration is being criticized for underwriting subprime loans, which critics say could lead to another wave of loan failures. Senior Editor Paddy Hirsch explains subprime lending and its inherent risks.

Ratings agencies are paid by the sellers of the securities they rate. Critics say there's a conflict of interest there. Senior Editor Paddy Hirsch explains.

Credit default swaps? They're complicated — and scary! The receipt you get when you pre-order your Thanksgiving turkey? Not so much. But they have a lot in common: They're both derivatives. Senior Editor Paddy Hirsch explains.

High-frequency trading is creating a ruckus on Wall Street. Marketplace Senior Editor Paddy Hirsch explains what high-frequency trading is and why some people are up in arms about it.

Dark pools are exchanges where people trade stocks anonymously. Senior Editor Paddy Hirsch explains how they work, and why the SEC is considering regulating them.

Cap and Trade is the linchpin of the government's effort to curb carbon emissions. Senior Editor Paddy Hirsch explains how the cap and trade model works.

In stories about the auto companies and the banks, we've been hearing about debt-to-equity swaps and exchanging preferred shares for common stock. To understand how those work, you need to understand a company's capital structure. Senior Editor Paddy Hirsch explains.

The shadow banking system is a key component of the U.S. economy, but the financial crisis has frozen it solid. Senior Editor Paddy Hirsch explains what shadow banking is and why it's important enough to warrant its own bailout, called the Term Asset-Backed Securities Loan Facility, or TALF.