Math - Most of your deals that are done as a stack are 3-4 month 1.5. The funder looks at it in terms of odds and margins. Your deals that go bad will probably pay for at least 30-60 days getting your principal back, and the deals that pay 100% are making up for the losses with the high margin. The second and third funder are not worried about the initial funder that put the money out for 6-12 months.

In some rare cases stacking does make sense. If you have a high volume merchant that the initial funder does not want to take the risk on and put out the total amount that the merchant would qualify for, it forces the merchant to continue shopping. When the second funder looks at the merchant and they still have another 10% of margin to work with on a payment, the deal makes sense.