i=0
stock = 100
cash = 0

for index, row in df2.iterrows():
    if df2.iloc[i][3] > df2.iloc[i+1][3]:
        if stock == 0:                             #future stock is cheaper, but no stock to sell
           continue
        else:
            cash = cash + df2.iloc[i][3] * stock   #future stock is cheaper, so sell
            stock = 0
    else:                                          #future stock is more expensive, so buy
        stock = round((cash/df2.iloc[i][3])-0.5)
       cash = round((cash - stock*df2.iloc[i][3])-0.5)
    i+=1
i