Reducing Portfolio Risk

The challenge of successfully managing an investment portfolio goes beyond making a series of good individual investment decisions.

Portfolio management requires paying attention to the portfolio as a whole, taking into account 

• diversification, 
• possible hedging strategies, and 
• the management of portfolio cash flow. 

In effect, while individual investment decisions should take risk into account, portfolio management is a further means of risk reduction for investors. 



1.  Appropriate Diversification 

Even relatively safe investments entail some probability, however small, of downside risk.

• The deleterious effects of such improbable events can best be mitigated through prudent diversification. 
• The number of securities that should be owned to reduce portfolio risk to an acceptable level is not great; as few as ten to fifteen different holdings usually suffice. 

Diversification for its own sake is not sensible. This is the index fund mentality: if you can't beat the market, be the market.

• Advocates of extreme diversification - which I think of as overdiversification - live in fear of company-specific risks; their view is that if no single position is large, losses from unanticipated events cannot be great. 
• My view is that an investor is better off knowing a lot about a few investments than knowing only a little about each of a great many holdings. 
• One's very best ideas are likely to generate higher returns for a given level of risk than one's hundredth or thousandth best idea. 

Diversification is potentially a Trojan horse. 

• Junk-bond-market experts have argued vociferously that a diversified portfolio of junk bonds carries little risk. Investors who believed them substituted diversity for analysis and, what's worse, for judgment. 
• The fact is that a diverse portfolio of overpriced, subordinated securities, about each of which the investor knows relatively little, is highly risky. 
• Diversification of junk-bond holdings among several industries did not protect investors from a broad economic downturn or credit contraction. 
• Diversification, after all, is not how many different things you own, but how different the things you do own are in the risks they entail. 

2.  Hedging 

Market risk - the risk that the overall stock market could decline - cannot be reduced through diversification but can be limited by hedging. An investor's choice among many possible hedging strategies depends on the nature of his or her underlying holdings.


A diversified portfolio of large capitalization stocks, for example, could be effectively hedged through the sale of an appropriate quantity of Standard & Poor's 500 index futures. 

• This strategy would effectively eliminate both profits and losses due to broad-based stock market fluctuations. 
• If a portfolio were hedged through the sale of index futures, investment success would thereafter depend on the performance of one's holdings compared with the market as a whole. 

A portfolio of interest-rate-sensitive stocks could be hedged by selling interest rate futures or purchasing or selling appropriate interest rate options.

A gold-mining stock portfolio could be hedged against fluctuations in the price of gold by selling  gold futures.

A portfolio of import- or export-sensitive stocks could be partially hedged through appropriate transactions in the foreign exchange markets. 



It is not always smart to hedge. 

• When the available return is sufficient, for example, investors should be willing to incur risk and remain unhedged. 
• Hedges can be expensive to buy and time-consuming to maintain, and overpaying for a hedge is as poor an idea as overpaying for an investment. 
• When the cost is reasonable, however, a hedging strategy may allow investors to take advantage of an opportunity that otherwise would be excessively risky. 
• In the best of all worlds, an investment that has valuable hedging properties may also be an attractive investment on its own merits. 

By way of example, from mid-1988 to early 1990 the Japanese stock market rose repeatedly to record high levels. The market's valuation appeared excessive by U.S. valuation criteria, but in Japan the view that the stock market was indirectly controlled by the government and would not necessarily be constrained by underlying fundamentals was widely held.

• Japanese financial institutions, which had become accustomed to receiving large and growing annual inflows of funds for investment, were so confident that the market would continue to rise that they were willing to sell Japanese stock market puts (options to sell) at very low prices. 
• To them sale of the puts generated immediate income; since in their view the market was almost certainly headed higher, the puts they sold would expire worthless. 
• If the market should temporarily dip, they were confident that the shares being put back to them would easily be paid for out of the massive cash inflows they had come to expect. 

Wall Street brokerage firms acted as intermediaries, originating these put options in Japan and selling them in private transactions to U.S. investors.' These inexpensive puts were in theory an attractive, if imprecise, hedge for any stock portfolio.

• Since the Japanese stock market was considerably overvalued compared with the U.S. market, investors in U.S. equities could hedge the risk of a decline in their domestic holdings through the purchase of Japanese stock market puts. 
• These puts were much less expensive than puts on the U.S. market, while offering considerably more upside potential if the Japanese market declined to historic valuation levels. 

As it turned out, by mid-1990 the Japanese stock market had plunged 40 percent in value from the levels it had reached only a few months earlier.

• Holders of Japanese stock market put options, depending on the specific terms of their contracts, earned many times their original investment. 
• Ironically, these Japanese puts did not prove to be a necessary hedge; the Japanese stock market decline was not accompanied by a material drop in U.S. share prices. 
• These puts were simply a good investment that might have served as a hedge under other circumstances.