Lesson 6 of 8
A margin against your own value
The margin of safety here is measured against a target price you set or a model you saved, and against nothing else. What changes when that value changes.
By Javier Sanz
Founder of ValueScreener. Built Ninety Nine, a securities services provider, and sold it to a tier-one global bank; ran operations and internationalization at Alpaca, the brokerage API.
Who writes thisEditorial processLinkedIn (opens in a new tab)X (opens in a new tab)
In one minute
- The margin of safety here is measured against the investor's own value: a target price they set, or a model they saved. There is no third source.
- With no value set, the rail is not applicable rather than breached, and the reader is told to set one.
- When the value changes, the rail is re-armed silently from the new reading, because a rail whose basis moved under it should not send an email.
Of all the figures a condition can be written on, this is the one where the definition matters most, because there are several definitions in circulation and only one of them is used here.
What the margin is measured against, and what it is not
The two permitted values
- A target price set on the thesis itself.
- The most recent discounted cash flow the investor saved.
Not a source of value here
None of these
- A vendor's own value estimate, retired on 2026-09-11.
- The margin measured against that estimate, retired with it.
- A price paid, which is a profit and loss figure and not a value.
- Any analyst consensus figure.
Only the left column exists in this product. Everything on the right was either retired or never used.
Why it is measured per thesis
Because a margin of safety is a statement about the gap between a price and a value, and a value is something a person holds. Two investors researching the same company will have different values and therefore different margins, and neither is more correct as a fact about the company.
Until 2026-09-11 the product carried a company-level margin built on a vendor's own model. It was withdrawn for two reasons that are worth knowing. Nobody could replay it, so nobody could say why it moved. And it was blind to share splits, so at least one company read a large positive margin against the same vendor's own current figure of the opposite sign.
The four states a margin rail can be in
Tested, when a value and a price both exist. Not applicable with no value set, which is the investor's own gap rather than the product's, and the reader is told to set a target price or save a model. Missing with a value but no price held tonight, which is the product's gap. And re-armed, which needs its own paragraph.
What happens when your value changes
The rail is re-armed silently. Its state is set from the new reading and nothing is sent.
The reason is that a breach email is supposed to mean a reason has broken. If a reader raises or lowers their own target price, the margin changes because they changed it, and an email reporting that back to them would be the product telling them what they just did.
A split is the exception that proves the rule: where a split has restated the value onto today's share count, the basis is still the value as the reader set it, because a split is not a new value.
Why this belongs in a credit course
Because a credit reading changes the value, not just the conditions. A company whose fifth-year maturity has no visible source of funds is a company where a reader's own model should carry a different discount rate or a different terminal assumption, and the margin computed from it moves accordingly.
That is a legitimate path from the bridge to a valuation, and it is the only one this track offers. The capstone on valuation takes it.
Check yourself
What is the margin of safety measured against here?
- A vendor's published value estimate
- The investor's own value: a target price they set, or a model they saved
- The price they paid
Show the answer
Answer: B.
The price paid is a profit and loss figure, not a value. The vendor estimate and the margin against it were both retired on 2026-09-11.An investor raises their own target price and the margin rises through its level. What is sent?
- A breach email, because the figure moved
- Nothing. The rail is re-armed silently from the new reading
- An inbox note confirming the change
Show the answer
Answer: B.
A breach email is supposed to mean a reason has broken. Reporting back a change the reader just made would be the product telling them what they did.A margin rail exists but no value has been set. What state is it in?
- Breached, because the margin cannot be confirmed
- Not applicable, with the reader told to set a target price or save a model
- Holding, until a value is set
Show the answer
Answer: B.
It is the investor's own gap rather than the product's, which is why it is counted as a refusal and not as a missing figure.Sources
- The product's own methodology page, for what the margin of safety is measured against and for the states a rail can be in.
- CLAUDE.md and the product's figure register, for the three figures retired on 2026-09-11 and the reasons each was withdrawn.
What this leaves out
- This is a heterodox tradition. The mainstream account of the same phenomenon differs, and nothing here is a forecast or a view on any security.
- The arithmetic is invented round numbers so it can be checked by hand. No company is described by it and no level in it is a level anybody should adopt.
- A margin of safety is only as good as the value behind it. A model with an optimistic input produces a comfortable margin, and the rail cannot tell the difference.
- Nothing here is advice about any security.