Investment thesis

A written statement of why an investment should work, what has to be true for it to work, and what would prove it wrong.

The useful version is short and falsifiable. Two or three sentences that a colleague could argue with, followed by the two or three conditions that would end it.

The thesis is also the monitoring instrument. Quarterly results are read against it rather than in isolation, which is what stops a position drifting from an investment into a habit.

If it takes a page to state, it is not a thesis.