How do I express a 1 year % change in closing price thru year 2016? (jan 1, 2016 thru dec 31, 2016)

Is the formula below correct?

((C'12/31/16'-O'01/01/16')/O'01/01/16')*100

Thanks,

No, use (C'12/30/16' - C'12/31/15') / C'12/31/15' * 100

The basic format of your formula is in fact correct.

That said, neither January 1, 2016 nor December 31, 2016 were trading days on the US stock markets. You would generally want to use trading days to write your formulas to make sure you get the expected results.

100 * (C'12/30/2016' / O'01/04/2016' - 1)

Changing the 12/30/2016 to 12/31/2016 doesn't make a difference, but using 01/01/2016 is actually going to get you the values from 12/31/2015 instead of 01/04/2016.

A better way to do this (at least during 2017 would be to use the following formula with a yearly time frame.

100 * (C1 / O1 - 1)

It is also generally customary to calculate the price percent change for the year from the close of the previous year and not the close of the current year. This would make the date version of the formula the following.

100 * (C'12/30/2016' / C'12/31/2015' - 1)

And the yearly bars ago version into the following.

100 * (C1 / C2 - 1)