def calculate_buy_and_hold_perc(df):
    """Uses the first closing price and closing price to determine
    the return percentage if the strategy was simply buy and hold.
    """
    first_close = df.iloc[0].close
    last_close = df.iloc[-1].close
    buy_and_hold_perc = (1 - (first_close / last_close)) * 100

    return round(buy_and_hold_perc, 3)