A one-year note pays twice the stock's rise up to 15%, so at most 30%, and loses one for one if the stock falls. Tabulate it against owning the stock for moves of minus 20%, 0, plus 10%, plus 15% and plus 40%.

The note beats the stock for any rise up to 30%, matches it at exactly 30%, and loses to it above; on the way down it is identical to the stock. At minus 20% both lose 20%. At zero both pay nothing. At plus 10% the note pays 20% against the stock's 10%. At plus 15% it pays its maximum, 30%. At plus 40% it still pays 30% while the stock earns 40%. The doubled rise is paid for by the cap and by the dividends the note does not pay.

Read the term sheet as three rules. Below zero, the note is the stock. Between zero and plus 15%, the note is twice the stock. Above 15%, the note is 30% whatever the stock does. Walk the five moves through those rules and the table below writes itself; the only line where people hesitate is plus 40%, where the cap binds.

The crossover is where the stock's straight line reaches the note's ceiling: a rise of 30%. Up to a 30% rise the note holder is ahead; at exactly 30% both earn 30%; above it the stock holder keeps every extra point and the note holder keeps none. A strong year for a mid-cap agro stock can run past 30%, so the cap is not a technicality. It is the scenario in which the client would most regret the switch, and the one the term sheet's headline, twice the upside, is designed to keep out of view.

Nothing in a term sheet is free, so find what pays for the doubling. Build the note from pieces: the stock itself, plus one at-the-money call that doubles the rise, minus two calls struck 15% higher that stop both lines at the cap. The two sold calls and the forgone dividend are what fund the extra at-the-money call; the client has sold the stock's upside above 30% and its dividend yield to buy twice the first 15%. It is the same bargain as a mobile plan with double data up to a limit and nothing beyond: generous for a typical month, expensive in the month you most needed it.

Two things the table does not show, and a careful answer names them. The note is an unsecured promise of the issuing bank, so if the issuer fails the client can lose regardless of what the stock did; the shares carry no such risk. And the note cannot be sold at the payoff value during the year; the bank will quote a price, and it will not be the table. Say the limitation plainly: this payoff holds at maturity, for a client who holds to maturity, with an issuer that is still standing.