Well, whether you keep your shares or sell them is a personal decision, little to do with finance, I reckon.

The only accurate valuation of a company is DCF. Basically, what is the dividend paid, multiply it up by a growth rate and then discount that at a fair rate of return.

Basically, it boils down to:

Value = Next Year’s Dividend / (fair rate of return - growth rate)

The problem is choosing the assumptions.

Growth rate - a long term rate, unlikely to be much more than GDP, so, let’s say 4%.

What is a fair dividend. Basically, what proportion of profits does not need to be paid out to maintain growth, i.e., what is left over after paying for upkeep of the business and investing in new schools, etc. Let’s assume last year’s profit of NT$1m, payout ratio of 40% (for a business like a school, maybe a much higher payout even.)

last years dividend = 1mn * 0.4 = 400,000

Next year’s dividend = 400,000 * 1.04 = 416,000

Rate of return. What is required to compensate for risk? Say 12%?

Value = 416,000 / (.12-.04) = 416,000 / (.08) = 5,200,000

Your share = 20% = 5.2m * 0.2 = 1,040,000 = NT$1.04m

Try this, altering the assumptions to what you think is right. Unfortunately, you will see a huge difference according to different assumptions. Raise the growth rate from 4% to 6% for example and the value of your share is nearly 1.4mn

Contrary to fox, i don’t think a five year payback is too unreasonable.

If you think all of these methods are converging to a reasonable number, and the assumptions are valid, then you have the answer. ultimately though, you can only work out what you are willing to sell at - what someone else is prepared to pay is another matter.