How is T-bill yield calculated? I opened a brokerage account with Charles Schwabb. The 9-month T-bill right now has a YTM of 5.47%. I wanted to buy $10,000 of it, however, the estimated total cost was $9620.22. This means I would only earn about $379.78 in interest right? But wouldn’t 5.47% of $10,000 for 9 months come out to be $410.25? Are there any hidden fees I didn’t know…