ELI5: Tranching

but...but...tranching still sounds difficult!

Think of this: Alice and Bob are two big whales. They both love yield farming and enjoy the high APY offered in the DeFi space. Alice is very aggressive with her capital: she likes putting her money into the latest yield farms that offer crazy high APY. Bob is conservative with his capital: he prefers having a guaranteed return of yield that endows him a stream of fixed cash flows over time.

The thing about yield farms is even DeFi’s biggest farms contain a certain risk of a full loss of capital due to protocol attacks, and the returns in yield farms often vary so that a guaranteed and predictable return is difficult to achieve.

To solve this, we ask Alice and Bob to bundle their capital together as a whole and deploy into farms, so they are now a farming fund which Alice and Bob have 50% of ownership to the fund respectively. Suppose the predicted APY is 20%, Alice and Bob should be splitting the yield half-half, getting 10% APY each. However, as Alice is looking for high yield and doesn’t really care about risks, while Bob is looking for low risk and predictable return, Alice and Bob can negotiate a deal: As the yield starts getting farmed, say 20%, Bob will receive a fixed amount of yield first, say 8%, and the rest of the yield, 12%, goes to Alice. This doesn’t seem fair right? Both contributed the same amount of capital however Bob is getting less yield than what he deserves. However, imagine now the yield farms perform poorly and the yield generated is only 15%. Bob will still get his fixed payment: 8%, while Alice’s only getting 7%.

Now you see the idea: Bob is sacrificing his some of his fair share (8% vs 12% under 20% APY situation) plus potential extra yield gains (8% vs 16% under 24% APY situation) to Alice in exchange for maintaining the stability of his yield returns, and hence Bob transferred his portion of yield volatility risk to Alice, which Alice accepts taking on the extra risk in exchange for higher returns under situations when yield is equal to or better than expected. If Alice did not enter such agreement, her share of yield will be split equally, getting only 10% instead of 12%.

Tranches, as a concept came from TradFi, can be viewed as categories of risk and rewards in a pool of capital: a senior tranche in Waterfall DeFi is the fixed yield return side with the highest priority to receiving interest payments (a pool of many Bobs); while a junior tranche is the variable yield return side with the lowest priority to receiving interest payments (a pool of many Alices). Through tranching a pool of capital put into DeFi yield farms, users will have the autonomy to choose their desired balance of risk versus rewards, or essentially, insuring their capital against yield volatility without upfront payment.