How much can I buy an I bond?

Electronic I bonds: $25 minimum or any amount above that to the penny. For example, you could buy an I bond for $36.73. Is there a maximum amount I can buy?

How often does the interest rate on a series I savings bond change?

The interest rate on a Series I savings bond changes every 6 months, based on inflation. The rate can go up. The rate can go down. The overall rate is calculated from a fixed rate and an inflation rate. The fixed rate never changes. The inflation rate is reset every 6 months and, therefore, so is the overall rate.

Are bond quotes updated in real-time?

Bond quotes are updated in real-time. Sources: FactSet, Tullett Prebon Commodities & Futures: Futures prices are delayed at least 10 minutes as per exchange requirements.