Python 算Beta值

我在算Beta值的时候用的这个代码

import yfinance as yf
stocklist = ['NVDA', '^GSPC']
start = '2021-01-01'
end = '2022-01-01'
data6 = yf.download(stocklist, start, end)['Adj Close']
data6


df1 = yf.download('NVDA', start, end)['Adj Close']

df2 = yf.download('^GSPC', start, end)['Adj Close']

#计算贝塔系数
s1 = df1
s2 = df2
print((np.cov(s1, s2))[0][1]/np.var(s2))

#得到答案0.18718850560702244

但是正确答案是2.0080349978119485
请问我哪里出了问题

公式是这个：