Does the fixed rate % part of the bond ever change? If so what makes it change? Do interest rates going up effect it's yield? How so? I am not talking about the inflation index rate which changes with inflation.
Well, the fixed rate for a given bond never changes. But the fixed rate for new issues changes every six months. I haven't seen them publish the algorithm, but it's probably based on the market average for 5-year TIPS. The 5-year real rate has inched up a bit (currently about 1.5%), so you'll probably see an increase in the fixed rate of i-bonds for the new issue in November.
Yes, I realize it doesn't go up after you purchase it. I am talking about when they issue new bonds. What is that rate tied to that makes it go up or down?
Blame the market. The real return is completely market driven. As I said, it's currently 1.5% for 5-year TIPS, and i-bonds are more-or-less 5-year TIPS, so I'm sure that's what the treasury uses to determine new issue rates (at least that's been true in the past).
OK then...some random imaginary number thats way too low, added to another imaginary number manipulated number that bears little resemblance to actual inflation