Determine the original value of the asset; that is, the value of the asset on Day 1. For instance, if you purchased a money market account for $10,000 on Day 1, the value of the asset on Day 1 is $10,000.
Determine the value of the asset on Day 2. Let's say your money market account grew to $10,050 in one day.
Take the difference between Day 1 and Day 2. The difference is $10,050 - $10,000 or $50.
Divide the difference by Day 1 for the ROI. The answer is $50 / $10,000 or 0.005.
Multiply by 100 for a daily percentage rate of return. The answer is 0.005 x 100 = 0.5 percent.