Valuation, asked the other way round
The price to earnings ratio asks how many dollars you pay for a dollar of profit. Free cash flow yield flips the question and asks what percentage of your purchase price comes back each year as cash the company genuinely has spare.
Because it is a percentage, it sits naturally next to other returns you might consider. A free cash flow yield of 5% invites an immediate comparison with what a savings account or a government bond pays, and that comparison is a useful piece of discipline when share prices are rising quickly.
Microsoft, worked out
Take free cash flow of roughly $74 billion against a market value of approximately $3.1 trillion. Divide 74 by 3,100 and multiply by 100, which gives a free cash flow yield of about 2.4%.
That is a low yield, and it is telling you something plainly: buyers are paying a substantial price for each dollar of cash the business currently produces, because they expect that cash to grow considerably. The number does not say whether they are right. It says what they are assuming.
Rounded recent approximations, used to show the calculation.
Remember which half is moving
Share prices move every day; cash flow is reported four times a year. Almost all short-term movement in this measure therefore comes from the price rather than from any change in the business.
That has a practical consequence. A yield that has climbed from 3% to 6% over a few months usually means the share price fell by half, not that cash flow doubled. Before treating a high yield as an opportunity, check which half of the fraction moved, and then ask why the market marked the price down.
The debt it quietly ignores
The version above compares cash flow with the value of the shares alone, which ignores what the company owes. Two businesses producing identical cash can look identically priced by this measure while one carries no borrowings and the other is heavily indebted.
The stricter approach replaces market value with enterprise value, which adds borrowings and subtracts cash on hand. That compares the cash flow against the true cost of owning the whole business, debts included, and it will rank an indebted company noticeably less attractively.
Using it in Stax
This measure pairs well with a quality filter. Asking for companies that both generate a respectable cash yield and earn a strong return on the capital they employ describes good businesses at sensible prices rather than cheap businesses in decline.
Once the rule exists, let Stax replay it over five or more years of real market prices, with fees deducted from every simulated trade. That is how you find out whether buying on cash yield helped, or whether it simply pointed you towards companies the market was right to doubt.