Year over year change in price

Hi all,

I'm trying to calculate the year over year change in a stock price for every date / row.  

In excel, this was much easier because I would:

 - Sort the tickers alphabetically

 - Verify if there was a stock price from the price year (e.g., offset 1 year)

 - Calculate the variance  

The current table has millions of rows and many stock prices

I am trying to create a column that shows the yoy change in closing price for any particular ticker on each date:

(Dec. 30 2016 closing price - Dec. 30 2015 closing price) / Dec. 30 2016 closing price for each stock

I'm very new to BI.  Below was my attempt at a measure...but has not been successful

YOY Difference = Calculate(sum('nasdaq_prices_2006-2015'[Closingprice]),dateadd('nasdaq_prices_2006-2015'[Date],-1,year))

Any help would be greatly appreciated!