DEFINITION of 'Rule Of 18'
A rule whereby the sum of the inflation rate and the P/E ratio of the Dow Jones Industrial Average is an indicator of the direction of the stock market. If the total is above 18, stocks are supposed to decrease. If the total is under 18, then the stock market is expected to increase.
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BREAKING DOWN 'Rule Of 18'
For example, if the P/E ratio for the Dow were 14 and the annual inflation rate were 3%, their sum would equal 17. This number would indicate that the stock market will increase.
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RELATED FAQS

What is the average pricetoearnings ratio in the banking sector?
Explore the price/earnings ratio in regard to the banking industry and learn what the average P/E ratio is for most banking ... Read Answer >> 
Stocks with high P/E ratios can be overpriced. Is a stock with a lower P/E always ...
The short answer? No. The long answer? It depends.The pricetoearnings ratio (P/E ratio) is calculated as a stock's current ... Read Answer >> 
What's the difference between absolute P/E ratio and relative P/E ratio?
The simple answer to this question is that absolute P/E, which is the most quoted of the two ratios, is the price of a stock ... Read Answer >> 
How can the pricetoearnings (P/E) ratio mislead investors?
A low P/E ratio doesn't automatically mean a stock is undervalued, just like a high P/E ratio doesn't necessarily mean it ... Read Answer >> 
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Where can I find the P/E ratios for the Dow and S&P 500?
When it comes to valuing stocks, the pricetoearnings (P/E) ratio is one of the oldest and most frequently used metrics. ... Read Answer >>