Holding Period Return

If an investors buy 4 shares of $100. In year 1 he sells 2 share for $100 each. and in year 2 he sells the remaining two shares for $200. Then what is his holding period return?

Year 1 = ($200 - $400)/$400 = -50%

Year 2= ($400-$200)/$200= 50%

HPY=(0.5*1.5)1/2 - 1

Is this correct?