Possible discrepancy between TreasuryDirect.gov Treasury Bill Investment Rate and Self-Calculated Interest Rate

I bought a 17 week treasury bill ending in Z93 as shown in the screenshot above. I placed 20,000 and after the discount rate, I paid 19707.13 for the treasury bill.

According to the screenshot, the investment rate is 4.558%

However, I decided to calculate the investment rate based on this calculation method in investopedia.com

20,000-19707.13 = 292.87. This is the discount spread.

292.87/19707.13 = 0.01486 or 1.486%.

The calculated 1.486% is significantly less than the stated 4.558%.

Wondering if someone could point out what I am missing here.

Also wondering what 'high rate' is from the first screenshot.

You bought a 17 week investment that pays 4.558% per year. That means you purchased 17 of the 52 weeks of the year or about 1/3 of the year.

So multiplying that 4.558% by (17/52) gives you an approximate rate of 1.49% and you calculated 1.486%. They are in the same ballpark.

Regarding the high rate. Some people don't take the market rate, they actually bid. The government gets more bids than they have bonds to sell. So the highest accepted bid was for the high rate. If they bid more than that they missed out on this auction.

From The US treasury:

Non-competitive Bidding

Maximum: \$10 million per auction. You agree to accept the rate, yield, or discount margin determined at the auction. If you are using your TreasuryDirect account, you must bid non-competitively.

Competitive Bidding

Maximum: 35% of the offering amount. You specify the rate, yield, or discount margin that you will accept. To bid competitively, you must use a bank, broker, or dealer — or your TAAPS account.