chart shows regular periodic contributions to a 401k plan and how the value changed 

Known as "Net Investment vs. Market Value," this chart helps illustrate for investors two important points: the total net investments within an account/plan or selected holding over time, and the corresponding market value fluctuation of those investments. Here, net investments are represented by the black line and correspond to cash flows resulting from the investor's own transactions. The market value of these investments is represented by the blue line and is a function of the daily price of each holding times the total number of units. Red shading (if any) indicates periods of negative unrealized gains where the value is less than what was invested. Green shading (if any) represents periods of positive unrealized gains where the value is greater than what was invested.