pd.io.json.json_normalize(data).pipe(
    lambda x: x.drop('ProductSMCP', 1).join(
        x.ProductSMCP.apply(lambda y: pd.Series(merge(y)))
    )
).rename(columns=lambda x: re.sub('(Product|Xref)\.', '', x))

  Currency Description Operational TypeLevel1 TypeLevel2       BBT SCSP  TCK _id SMCP SMCP2
0      NaN      3 YEAR         NaN   INTEREST       LONG       NaN   96  NaN  25   01   NaN
1      USD     10 YEAR        True   INTEREST       LONG  CITITYM9  NaN   ZN  26   01    02