Ok..I got some old materials and I am reviewing them (I am planning to seat again for the CFA & FRM).Now, the CFA materials Level I 2010, Vol 4 "Corporate Finance & Portfolio Management" Example 2 "Computing Investment Yields", page 108 on BEY states:For a 91 days $100K US TBill sold at discount rate of 7.91%, calculate:a) Money market yiledb) Bond equivalent yieldSo far, so good; now for the Money market you can go like this:(This is my own method, so to speak):MM yield = [1/(1-7.91%*(91/360)) -1]* (360/91) = 8.071% (since for money markets instruments, the yield convention is 360/actual)No problem there, NOW.for part b I think (given bond convention is 365/actual) the calculations should be:BEY = [1/(1-7.91%*(91/365)) -1]* (365/91) = 8.069%The CFA materials stated that the solution is:BEY = [1/(1-7.91%*(91/360)) -1]* (365/91) = 8.183%Is this correct?

Yes. US T Bills use 360 days, US T bonds 365 days. The BEY formula has to convert from one to the other and that is why you see both a "360" and a "365" appearing in the second formula.

Got it. In both cases, the buyer got T-BILLS.