Collateralized loan obligation
Collateralized loan obligations (CLOs) are a form of securitization where payments from multiple middle sized and large business loans are pooled together and passed on to different classes of owners in various tranches. A CLO is a type of collateralized debt obligation.
Each class of owner may receive larger payments in exchange for being the first in line to lose money if the businesses fail to repay the loans. The actual loans used are generally multi-million dollar loans known as syndicated loans, usually originally lent by a bank with the intention of the loans being immediately paid off by the collateralized loan obligation owners. The loans are usually "leveraged loans", that is, loans to businesses which owe an above average amount of money for their kind of business, usually because a new business owner has borrowed funds against the business to purchase it (known as a "leveraged buyout") or because the business has borrowed funds to buy another business.
The reason behind the creation of CLOs was to increase the supply of willing business lenders, so as to lower the price (interest costs) of loans to businesses and to allow banks more often to immediately sell loans to external investor/lenders so as to facilitate the lending of money to business clients and earn fees with little to no risk to themselves. CLOs accomplish this through a 'tranche' structure. Instead of a regular lending situation where a lender can earn a fixed interest rate but be at risk for a loss if the business does not repay the loan, CLOs combine multiple loans but don't transmit the loan payments equally to the CLO owners. Instead, the owners are divided into different classes, called "tranches", with each class entitled to more of the interest payments than the next, but with them being ahead in line in absorbing any losses amongst the loan group due to the failure of the businesses to repay. Normally a leveraged loan would have a fixed interest rate, but potentially only a certain lender would feel that the risk of loss is worth the interest that is charged. By pooling multiple loans and dividing them into tranches, in effect multiple loans are created, with relatively safe ones being paid lower interest rates (designed to appeal to conservative investors), and higher risk ones appealing to higher risk investors (by offering a higher interest rate). The whole point is to lower the cost of money to businesses by increasing the supply of lenders (attracting both conservative and risk taking lenders).
CLOs were created because the same "tranching" structure was invented and proven to work for home mortgages in the early 1980s. Very early on, pools of residential home mortgages were turned into different tranches of bonds to appeal to various forms of investors. Corporations with good credit ratings were already able to borrow cheaply with bonds, but those that couldn't had to borrow from banks at higher costs. The CLO created a way for companies with weaker credit ratings to borrow from more institutions than just banks, lowering the overall cost of money to them.
The market for U.S. collateralized loan obligations was truly reborn in 2012, however, hitting $55.2 billion, with new-issue CLO volume quadrupling from the previous year, according to data from Royal Bank of Scotland analysts. Big names such as Barclays, RBS and Nomura launched their first deals since before the credit crisis; and smaller names such as Onex, Valcour, Kramer Van Kirk, and Och Ziff ventured for the first ever time into the CLO market, reflecting the rebounding of market confidence in CLOs as an investment vehicle. CLO issuance has soared since then, culminating in full-year 2013 CLO issuance in the U.S. of $81.9 billion, the most since the pre-Lehman era of 2006-07, as a combination of rising interest rates and below-trend default rates drew massive amounts of capital to the leveraged loan asset class. 
Issuance in 2014 has picked up where it left off in 2013, with roughly $11.5 billion in CLO vehicles priced during the first few months of the year.
- Collateralized debt obligation, securitization vehicle for various debt instruments
- Collateralized fund obligation, securitization vehicle for private equity and hedge fund assets
- Collateralized mortgage obligation, securitization vehicle for residential mortgages
- "CLOs/Institutional Investors". Leveraged Loan Primer | LCD.
- Miller, Steve (2014-01-02). "2013 CLO Issuance Hits $81.9B; Most Since 2007". Forbes.
- "Busy times for U.S. CLO market; $11.49B in first two months of 2014". LeveragedLoan.Com.