df['MA'] = df.rolling(window=5).mean()
print(df)
# Value MA
# Date
# 1989-01-02 6.11 NaN
# 1989-01-03 6.08 NaN
# 1989-01-04 6.11 NaN
# 1989-01-05 6.15 NaN
# 1989-01-09 6.25 6.14
# 1989-01-10 6.24 6.17
# 1989-01-11 6.26 6.20
# 1989-01-12 6.23 6.23
# 1989-01-13 6.28 6.25
# 1989-01-16 6.31 6.27