Question for traders familiar with yield spreads. Let's say I want make a fly (to trade or just to monitor). So, I want to buy notes / sell bonds AND sell bonds / buy ultra bonds This means I bought the NoB spread and sold the BoB spread. Using these ratios The cash value of all contracts would be given by 5000*ZN - 5000*ZB + 2000*UB Do any of you guys know what the most common way to weight this type of trade is? What do you think about these weightings? (or others like this) Thanks.