The Trouble with VAR is Related to Length

The Trouble with VAR is Related to Length

The trouble with VAR and other mathematical models of risk is that if it becomes the dominant paradigm, and everyone begins to use it, it creates distortions in the market, because institutions gravitate to asset classes that the model makes to appear artificially cheap.  Then after a self-reinforcing cycle that boosts that now favored asset class to an unsupportable level, the cashflows underlying the asset can no longer support it, the market goes into reverse, and the VAR models encourage an undershoot.  The same factors that lead to buying to an unfair level also cause selling to an unfair level.


Benchmarking and risk control through VAR only work when few market participants use them.  When most people use them, it becomes like the portfolio insurance debacle of 1987.  VAR becomes pro-cyclical at that point.

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Sometimes I think the Society of Actuaries is really dumb.  The recent financial crisis demonstrated the superior power of long-term actuarial stress-testing versus short-term quant models for analyzing risk.  The actuarial profession has not taken advantage of this.  Now, maybe some investment bank could adopt an actuarial approach to risk, and they will be much safer.  But guess what?  They won’t do it because it will limit risk taking more than other investment banks.  Unless the short-term risk model is replaced industry-wide with a long-term risk model, in the short-run, the company with the short-term risk model will do better.

The reason why VAR does not effectively control risk is simple.  VAR is a short-term measure in most of its implementations.  It is a short-term measure of risk for short- and long-term assets.  Just as long-term assets should be financed with long-term liabilities, so should risk analyses be long-term for long-term assets.

This mirrors financing as well, because bubbles tend to occur when long-term assets are financed by short-term liabilities.  Risk gets ignored when long-term assets are evaluated by short-term price movements.

And, as noted above, these effects are exacerbated when a lot parties use them; a monocultural view of short-run risk will lead to booms and busts, much as portfolio insurance caused the crash in 1987.  If a lot of people trade in such a way as to minimize losses at a given level, that sets up a “tipping point” where the market will fall harder than anyone expects, should the market get near that point.

The idea that one can use a short-term measure of risk to measure long-term assets assumes that markets are infinitely deep, and that there are no games being played.  You have the capacity to dump/acquire the whole position at once with no frictional costs.  Ugh.  Today I set up a new client portfolio, and I was amazed at how much jumpiness there was, even on some mid-cap stocks.  Liquidity is always limited for idiosyncratic investments.

The upshot here is simple: with long term assets like stocks, bonds, housing, the risk analysis must be long term in nature or you will not measure risk properly, and you will exacerbate booms and busts.  It would be good to press for regulations on banks to make sure that all risk analyses are done to the greater length of the assets or the liabilities (and with any derivatives, on the underlying, not contract term).

By David Merkel, CFA of Aleph Blog

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David J. Merkel, CFA, FSA — 2010-present, I am working on setting up my own equity asset management shop, tentatively called Aleph Investments. It is possible that I might do a joint venture with someone else if we can do more together than separately. From 2008-2010, I was the Chief Economist and Director of Research of Finacorp Securities. I did a many things for Finacorp, mainly research and analysis on a wide variety of fixed income and equity securities, and trading strategies. Until 2007, I was a senior investment analyst at Hovde Capital, responsible for analysis and valuation of investment opportunities for the FIP funds, particularly of companies in the insurance industry. I also managed the internal profit sharing and charitable endowment monies of the firm. From 2003-2007, I was a leading commentator at the investment website Back in 2003, after several years of correspondence, James Cramer invited me to write for the site, and I wrote for RealMoney on equity and bond portfolio management, macroeconomics, derivatives, quantitative strategies, insurance issues, corporate governance, etc. My specialty is looking at the interlinkages in the markets in order to understand individual markets better. I no longer contribute to RealMoney; I scaled it back because my work duties have gotten larger, and I began this blog to develop a distinct voice with a wider distribution. After three-plus year of operation, I believe I have achieved that. Prior to joining Hovde in 2003, I managed corporate bonds for Dwight Asset Management. In 1998, I joined the Mount Washington Investment Group as the Mortgage Bond and Asset Liability manager after working with Provident Mutual, AIG and Pacific Standard Life. My background as a life actuary has given me a different perspective on investing. How do you earn money without taking undue risk? How do you convey ideas about investing while showing a proper level of uncertainty on the likelihood of success? How do the various markets fit together, telling us us a broader story than any single piece? These are the themes that I will deal with in this blog. I hold bachelor’s and master’s degrees from Johns Hopkins University. In my spare time, I take care of our eight children with my wonderful wife Ruth.
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