Currently, my IRA is flat on the year compared to an 8% or so gain for the S&P 500 and a 17% gain for Berkshire. Select Comfort (-37.5%) and First Marblehead (-28.25%) are the primary culprits, though Canon is somehow down 11% on the year too. Now I don't like the idea of seeing my portfolio stagnate, but there is a ray of hope here: my IRA's earnings yield is improving.

Here's how I calculate yield for my portfolio. Each quarter, I multiply the EPS for each company I own by the number of shares I hold at the end of the quarter. I add up those numbers and at the end of the year I have a value for "look-through" earnings. That's how much my stocks would have returned if they had paid out 100% of earnings in the form of a cash dividend. For 4^{th} quarter earnings, I use analyst or company estimates which are decent first-order guesses. Then I divide by the total value of my portfolio to get look-through yield.

Yield 2007 2006 2005 2004 2003 2002 ----- ------ ------ ------ ------ ------ ------ Look-through 4.57% 3.90% 5.22% 3.65% 3.20% 2.59%

Since my account value has not changed significantly since the beginning of the year, the increase in yield is entirely due to increases in my companies' earnings. This measure does not include income from cash in the numerator, but it does include cash in the denominator. That means, cash-heavy portfolios are penalized. One solution would be to subtract cash from the denominator. A better solution is to add in interest earned to the numerator. I also add in premiums from call options, profits from short-term arbitrages, and cash dividends, while subtracting commissions, fees, and option losses. This produces a sort of operating earnings yield:

Yield 2007 2006 2005 2004 2003 2002 ----- ------ ------ ------ ------ ------ ------ Look-through 4.57% 3.90% 5.22% 3.65% 3.20% 2.59% Operating 6.21% 5.76% 5.46% 3.70% 1.97% 1.74%I know this double counts cash dividends, which are also reflected in look through earnings. Notice that my cash position has added to earnings in the last two years thanks to a number of arbitrage opportunities.

Higher yields indicate a sort of potential energy for a portfolio. Like the spring in a windup toy, increasing earnings give a portfolio a chance to run. Over a long period of time and given more or less efficient markets, an increase in earnings would represent a corresponding increase in price. Imagine what would happen to a company that earned 50¢ a share and sold for $10 were to increase earnings to $1 a share. If the yield remained at 5%, the stock would also double to $20. But until those gains are realized by selling the stock, that $10 a share increase will not be released. In order to calculate the effects of buying low and selling high, I add in realized gains and special dividends (like the one Sally Beauty distributed last year).

Yield 2007 2006 2005 2004 2003 2002 ----- ------ ------ ------ ------ ------ ------ Look-through 4.57% 3.90% 5.22% 3.65% 3.20% 2.59% Operating 6.21% 5.76% 5.46% 3.70% 1.97% 1.74% Net 12.84% 18.31% 5.46% 3.70% 12.92% 1.74%

Unfortunately, the net yield is extremely choppy. The simplest solution is to take the geometric mean, which is the best way to get an average of rates or percentages:

Yield 2007 2006 2005 2004 2003 2002 ----- ------ ------ ------ ------ ------ ------ Look-through 4.57% 3.90% 5.22% 3.65% 3.20% 2.59% Operating 6.21% 5.76% 5.46% 3.70% 1.97% 1.74% Net 12.84% 18.31% 5.46% 3.70% 12.92% 1.74% Geomean 6.89% 6.08% 4.62% 4.36% 4.74% 1.74%This smooths the data to show that net yields are also creeping up for my portfolio.

So what does all this mean? In my opinion, these yields are a rough estimate of potential. As I make good investments in companies that are cheap and have high earnings, my portfolio potential goes up. When I'm able to make money with the cash potion of the account, as I have over the last few years, I increase my portfolio's potential a bit more. When I harvest some of that potential by selling positions or receiving special distributions from a position, I have a chance to reinvest in companies with increased earnings potential. As I make good choices in allocating assets, my portfolio's yield and potential increase.

It's important to look at measures besides stock value when considering changes in investments. At the moment, First Marblehead and Select Comfort have the highest earnings yield, but are my worst performers. Oracle has the lowest yield, but is also one of the bright spots in terms of price performance. A narrow focus on recent price movement (momentum investing) would lead me to cut my losers and ride my winners. But as a contrarian investor, I'm looking to sell Oracle (low potential) and buy First Marblehead (high potential).