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033A lender's shares trade at 3 times book value and it earns a 15% return on equity. What P/E is that? If its ROE falls to 12% and the price-to-book stays at 3 times, what happens to the P/E?Equity research at AMCsGlobal asset managers
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Before you work it: what P/E does 3 times book and a 15% ROE imply?
Show the worked solution
A P/E of 20x, rising to 25x if ROE falls to 12% while the P/B stays at 3. Earnings are ROE times book value, so P/E equals P/B divided by ROE: 3 over 0.15 is 20. At 12% ROE the same P/B gives 3 over 0.12, or 25. The shares look no dearer on book, but each rupee of earnings now costs 25% more.
How do P/B and ROE give you the P/E?
Suppose a shop is sold for three times the money the owner has put into it, and the shop earns 15% a year on that money. A buyer paying 300 for every 100 put in gets 15 of profit a year for her 300, which is 20 years of profit. ROE is the bridge between book value and earnings, so P/E is simply P/B divided by ROE. Price sits on top of both ratios, and it cancels.
The relationshipP/B price to book value per share, 3.0 ROE earnings divided by book value, 15% then 12% P/E price to earnings per share What it says in wordsDivide price-to-book by the return on equity and you have price-to-earnings.With book value of Rs 100 a share and a price of Rs 300, a 15% ROE gives earnings of Rs 15 and a P/E of 20x. If ROE falls to 12% and the P/B stays at 3, earnings drop to Rs 12 and the same price becomes a P/E of 25x. What does an unchanged P/B after a fall in ROE tell you?
If returns fall and the price-to-book does not, the shares have become more expensive per rupee of profit, even though nothing on the book-value screen moved. For a lender, book value is the natural anchor, and many investors screen on P/B alone. This is the case where that screen misleads: the same 3.0x now buys 12% returns instead of 15%. To hold a 20x P/E at 12% ROE, the P/B would have to fall to 2.4x.
There are fair reasons the market might hold the P/B: it may expect ROE to recover, or the fall may be a one-off provision. Say that, then say the test: if ROE stays at 12%, a P/B of 3.0 is paying for returns that are no longer there. The ratios here are illustrations; the relationship holds for any company whose book value is meaningful.
Where candidates lose it
The common slip is multiplying instead of dividing: 3 times 0.15 gives 0.45, which some candidates then misread as 4.5x. Earnings are smaller than book here, so the P/E has to be larger than the P/B, not smaller. A quick sense check catches it.
The second trap is saying the P/E falls when ROE falls, because lower returns sound cheaper. With the price and book unchanged, lower earnings mean a higher P/E.
What the interviewer asks next
- What P/B would keep the P/E at 20x if ROE is 12%?
- If the cost of equity is 12%, what does a 12% ROE suggest about a fair P/B for a lender that does not grow?
- Why do analysts value lenders on P/B more often than on P/E?
