pPRIME cannot pay less than about 7%, because that floor is set outside the pool by what investors can earn elsewhere. Senior is the largest layer, so it sets most of the cost of funds. Work backwards and a pool needs roughly 15–17% gross on the underlying loans to pay the senior layer, the junior layers, the losses, the fees and still leave the originator a return worth having.

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The chain of constraints

1

Maple pays ~5% at near-zero risk

On overcollateralised, zero-loss, instantly redeemable paper.
2

So pPRIME has a floor around 7%

An unrated receivables pool must pay meaningfully more, or there is no reason to hold it.
3

Senior is the largest layer

So that floor drives most of the blended cost of funds.
4

Add the junior layers, losses and fees

pCORE at ~11%, pALPHA at ~16%, plus assumed losses and PRISM’s fees.
5

The book must earn 15–17% gross

Anything less does not leave the originator a return worth having.

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What this rules out

This rules out safe, low-yield assets. Invoice finance against large rated corporates earns about 10% and cannot support the structure, even with a layer removed and every rate cut.
That is a real constraint on what PRISM can fund, not a preference. It means PRISM is structurally limited to higher-yielding books — invoice financiers, BNPL lenders, merchant financiers — and the credit risk that comes with them. It is also why a loan book earning at least 15% gross is a hard requirement for originators.