DSO is days to collect, DIO days of stock held, DPO days taken to pay suppliers, and the cash conversion cycle is DSO plus DIO minus DPO — the days between paying for inputs and being paid for outputs.
A negative cash conversion cycle, as supermarkets and many subscription businesses run, means growth is self-funding: expansion generates cash rather than consuming it. That structural feature justifies a real multiple premium and is one of the most durable long characteristics available.
Track each component quarter by quarter, comparing the same quarter year over year to strip seasonality. Deterioration in DSO or DIO leads reported earnings trouble by two to four quarters in most industries — precisely the window in which a short is established at a good price.
Educational, not investment advice.