import pandas as pd

def fun():
    raw_data = pd.read_csv("result_total_ret.csv").dropna()
    data = []
    for date in raw_data['DataDate'].unique():
        df = raw_data[raw_data['DataDate'] == date].sort_values(by = ['trt1y'], ascending=[False])
        new_elem = {
            'winners': df[:len(df)//10],
            'losers': df[len(df)//10:]
        }
        data.append(new_elem)
    return data