What Is Average Life?

The average life is the length of time the principal of a debt issue is expected to be outstanding. Average life does not take into account interest payments, but only principal payments made on the loan or security. In loans, mortgages, and bonds, the average life is the average period of time before the debt is repaid through amortization or sinking fund payments.

Investors and analysts use the average life calculation to measure the risk associated with amortizing bonds, loans, and mortgage-backed securities. The calculation gives investors an idea of how quickly they can expect returns and provides a useful metric for comparing investment options. In general, most investors will choose to receive their financial returns earlier and will, therefore, choose the investment with the shorter average life.

Understanding Average Life

Also called the weighted average maturity and weighted average life, the average life is calculated to determine how long it will take to pay the outstanding principal of a debt issue, such as a Treasury Bill (T-Bill) or bond. While some bonds repay the principal in a lump sum at maturity, others repay the principal in installments over the term of the bond. In cases where the bond’s principal is amortized, the average life allows investors to determine how quickly the principal will be repaid.

The payments received are based on the repayment schedule of the loans backing the particular security, such as with mortgage-backed securities (MBS) and asset-backed securities (ABS). As borrowers make payments on the associated debt obligations, investors are issued payments reflecting a portion of these cumulative interest and principal payments.

Calculating the Average Life on a Bond

To calculate the average life, multiply the date of each payment (expressed as a fraction of years or months) by the percentage of total principal that has been paid by that date, add the results, and divide by the total issue size.

For example, assume an annual-paying four-year bond has a face value of $200 and principal payments of $80 during the first year, $60 for the second year, $40 during the third year, and $20 for the fourth (and final) year. The average life for this bond would be calculated with the following formula:

($80 x 1) + ($60 x 2) + ($40 x 3) + ($20 x 4) = 400

Then divide the weighted total by the bond face value to get the average life. In this example, the average life equals 2 years (400 divided by 200 = 2).

This bond would have an average life of two years against its maturity of four years.

Mortgage-Backed and Asset-Backed Securities

In the case of an MBS or ABS, the average life represents the average length of time required for the associated borrowers to repay the loan debt. An investment in an MBS or ABS involves purchasing a small portion of the associated debt that is packaged within the security.

The risk associated with an MBS or ABS centers on whether the borrower associated with the loan will default. If the borrower fails to make a payment, the investors associated with the security will experience losses. In the financial crisis of 2008, a large number of defaults on home loans, particularly in the subprime market, led to significant losses in the MBS arena.

Special Considerations

While certainly not as dire as default risk, another risk bond investors face is prepayment risk. This occurs when the bond issuer (or the borrower in the case of mortgage-backed securities) pays back the principal earlier than scheduled. These prepayments will reduce the average life of the investment. Because the principal is paid back early, the investor will not receive future interest payments on that part of the principal.

This interest reduction can represent an unexpected challenge for investors of fixed-income securities dependent on a reliable stream of income. For this reason, some bonds with payment risk include prepayment penalties.

Who Is Alan Greenspan?

Alan Greenspan is an American economist who was the chair of the Board of Governors of the Federal Reserve (Fed), the United States’ central bank, from 1987 until 2006. In that role, he also served as the chair of the Federal Open Market Committee (FOMC), which is the Fed’s principal monetary policymaking committee that makes decisions on interest rates and managing the U.S. money supply.

Greenspan is best known for largely presiding over the Great Moderation, a period of relatively stable inflation and macroeconomic growth, that lasted from the mid-1980s to the financial crisis in 2007.

Early Life and Education

Alan Greenspan was born in New York City on March 6, 1926. He received his bachelor’s, master’s, and doctoral degrees in economics, all from New York University, as well as studying economics at Columbia University in the early 1950s under Arthur Burns, who would later serve two consecutive terms as chair of the Board of Governors of the Fed.

Greenspan’s first job, in 1948, was not in government but for a non-profit analyzing demand for steel, aluminum, and copper. After this, Greenspan ran an economic consulting firm in New York City, Townsend-Greenspan & Co., Inc., from 1954 to 1974 and 1977 to 1987. Greenspan began his career in the public sector in 1974 when he served as chair of the President’s Council of Economic Advisers (CEA) under President Gerald Ford.

In 1987, Greenspan became the 13th chair of the Fed, replacing Paul Volcker. President Ronald Reagan was the first to appoint Greenspan to the office, but three other presidents, George H.W. Bush, Bill Clinton, and George W. Bush, named him to four additional terms. His tenure as chair lasted for more than 18 years before he retired in 2006 to be replaced by Ben Bernanke. After leaving, he published his memoir, The Age of Turbulence, and began his own Washington DC-based consulting firm, Greenspan Associates LLC. 

Alan Greenspan was known as being adept at gaining consensus among Fed board members on policy issues and for serving during one of the most severe economic crises of the late 20th century, the aftermath of the stock market crash of 1987. After that crash, he advocated for sharply slashing interest rates to prevent the economy from sinking into a deep depression.

Alan Greenspan’s Policies and Actions

Greenspan presided over one of the most prosperous periods in American history—thanks in no small part, supporters feel, to his helming of the Fed. Still, some of his policies and actions were controversial, either at the time or in retrospect.

Views on Inflation

Early in his career, Greenspan developed a reputation for being hawkish on inflation, in part due to his advocacy for a return to the gold standard in monetary policy in the 1967 essay “Gold and Economic Freedom.” 

His allegedly “hawkish” stance was portrayed by early critics as a preference for sacrificing economic growth in exchange for preventing inflation. Greenspan eventually reversed those views as Fed chief; in a 1998 speech, he conceded that the new economy might not be as susceptible to inflation as he had first thought.

In practice, Greenspan’s supposedly hawkish approach was flexible, to say the least. He was clearly willing to risk inflation under conditions that could create a severe depression and certainly pursued a generally easy money policy relative to his predecessor, Paul Volcker. In particular, in the early 2000s, Greenspan presided over cutting interest rates to levels not seen in many decades.

Flip-Flop on Interest Rates

In 2000, Greenspan advocated reducing interest rates after the dot-com bubble burst. He did so again in 2001 after 9-11, the World Trade Center attack. Following 9-11, Greenspan led the FOMC to immediately reduce the Fed funds rate from 3.5% to 3%, and, in the following months, he worked toward lowering that rate to a record (at the time) low of 1.13% and holding it there for a full year.

Some criticized those rate cuts as having the potential to inflate asset price bubbles in the U.S. Greenspan’s pro-inflationary policies, particularly during this period, are today generally understood to have contributed to the U.S. housing bubble, subsequent subprime mortgage financial crisis, and the Great Recession, though this is of course disputed by Greenspan and his allies.

Encouraging Adjustable-Rate Mortgages

In a 2004 speech, Greenspan suggested more homeowners should consider taking out adjustable-rate mortgages (ARMs) where the interest rate adjusts itself to prevailing market interest rates. Under Greenspan’s tenure, interest rates subsequently rose as inflation accelerated. This increase reset many of those mortgages to much higher payments, creating even more distress for many homeowners and exacerbating the impact of that crisis.

The “Greenspan Put”

The “Greenspan put” was a monetary policy strategy popular during the 1990s and 2000s under Greenspan. Throughout his reign, he attempted to help support the U.S. economy by actively using the federal funds rate to aggressively lower interest rates to fight the deflation of asset price bubbles.

The Greenspan put created a substantial moral hazard in financial markets. Informed investors could expect the Fed to take predictable actions that would bailout investor’s losses, which distort the incentives of market participants. This created an environment where investors were encouraged to take excessive risk because Fed monetary policy tended to inherently limit their potential losses in the event of a market downturn in an analogous way to buying put options on the open market.

The Bottom Line

Like many other government officials, the success of Alan Greenspan’s five terms as Chair of the Fed will depend on who you ask. However, it is certainly true that Greenspan faced some massive challenges during his tenure, such as the 1987 stock market crash and the attacks on the World Trade Center.

Overall, Greenspan helped usher in a strong U.S. economy in the 1990s. Opinion on how much his actions caused the economic recession that began shortly after his term ended varies.