Friday to Friday is correct (close of the week to close of the following week) Friday's close is $1000 Monday is $1025 Tuesdayis $1050 Wednesday $1075 Thursday $1085 Friday $1100 ....Friday's close Profit is $100 and % is $100/$1000 or 10%

Friday to Friday is correct (close of the week to close of the following week)

Suppose the following closing prices

• Friday: \$1,000
• Monday: \$1,025
• Tuesday: \$1,050
• Wednesday: \$1,075
• Thursday: \$1,085
• Friday: \$1,100

Then, Friday's close profit is \$100 and the return is $\frac{\\\$100}{\\\$1000}=10\%$.