投资范围包括纽交所、美国证券交易所和纳斯达克的股票,回测数据来自Compustat。剔除市值低于纽交所第20百分位的股票。资产增长变量定义为年度总资产变化百分比,基于t-2到t-1年的数据计算。每月按资产增长排序为十分位,选择资产增长最高的股票,再根据过去11个月的回报率(不包括上个月)将其分为五分位。投资者做多动量最强的股票,做空动量最弱的股票,组合等权分配,每月重新平衡。多空组合仅在2月至12月持有,1月不交易。

策略概述

投资范围包括纽交所、美国证券交易所和纳斯达克的股票(用于回测的数据来自Compustat)。市值低于纽交所第20百分位的股票被剔除。资产增长变量定义为资产负债表总资产的年度百分比变化,使用t-2到t-1年的数据计算资产增长,截止月为7月。每月,股票按资产增长排序为十分位,选择资产增长最高的股票。然后根据过去11个月的回报率(排除上个月的表现)将最高资产增长的股票再分为五分位。投资者会做多动量最强的股票,做空动量最弱的股票。投资组合等权分配,每月重新平衡。投资者仅在2月至12月持有多空组合,1月被排除,因为这一月经常被证明对动量策略不利(见《1月效应筛选与股票动量》)。

策略合理性

学术研究表明,现有文献并没有明确说明为何用资产增长衡量的公司投资应与回报持续性相关。然而,这项学术研究的结果具有高度的统计显著性,且基于长期的数据样本。资产增长与动量的互动在包含多项控制变量的情况下依然显著。因此,对该组合策略的信心可能较高。

论文来源

Firm Expansion and Stock Price Momentum [点击浏览原文]

<摘要>

我们记录了公司层面资产变化与回报动量之间显著且稳健的联系。对于经历了大规模资产扩张或收缩的公司,动量利润巨大且显著,而对于其他公司,动量利润通常较小且不显著。这一互动模式不被先前记录的动量驱动因素所覆盖,并出现在先前文献中记录的无动量利润的市场状态中。此外,我们发现总资产增长与回报动量之间存在正向的时间序列关系,且总资产增长的效应强于与商业周期和投资者情绪相关的变量。尽管现有的大多数公司投资与动量模型无法解释我们的结果,但最近的实物期权模型似乎最有前景。

回测表现

年化收益率16.77%
波动率13.84%
Beta-0.146
夏普比率-0.237
索提诺比率-0.231
最大回撤81.2%
胜率50%

完整python代码

from AlgoLib import *
import numpy as np
from pandas.core.frame import DataFrame
from pandas.core.series import Series

class MomentumFactorAssetGrowthEffect(XXX):

    def Initialize(self) -> None:
        self.SetStartDate(2000, 1, 1)
        self.SetCash(100_000)

        self.UniverseSettings.Leverage = 5
        self.UniverseSettings.Resolution = Resolution.Daily
        self.AddUniverse(self.FundamentalSelectionFunction)
        self.Settings.MinimumOrderMarginPortfolioPercentage = 0.0

        self.exchange_codes: list[str] = ['NYS', 'NAS', 'ASE']
        self.fundamental_count: int = 1_000
        self.fundamental_sorting_key = lambda x: x.MarketCap
        self.months_in_year: int = 12
        self.days_in_month: int = 21
        self.total_assets_history_period: int = 2
        self.decile: int = 10
        self.quintile: int = 5
        self.excluded_month: int = 1
        
        # Monthly close prices and total assets
        self.symbol_data: dict[Symbol, SymbolData] = {}
        self.long_symbols: dict[Symbol] = []
        self.short_symbols: dict[Symbol] = []
        self.selection_flag: bool = False

        market: Symbol = self.AddEquity('SPY', Resolution.Daily).Symbol        
        self.Schedule.On(self.DateRules.MonthStart(market), 
                        self.TimeRules.AfterMarketOpen(market), 
                        self.Selection)

    def FundamentalSelectionFunction(self, fundamental: List[Fundamental]) -> List[Symbol]:
        if not self.selection_flag:
            return Universe.Unchanged

        # Update the rolling window every month.
        for security in fundamental:
            if security.Symbol in self.symbol_data:
                self.symbol_data[security.Symbol].update_price(security.AdjustedPrice)

        filtered: list[Fundamental] = [f for f in fundamental if f.HasFundamentalData
                                        and f.SecurityReference.ExchangeId in self.exchange_codes
                                        and not np.isnan(f.FinancialStatements.BalanceSheet.TotalAssets.TwelveMonths)
                                        and f.FinancialStatements.BalanceSheet.TotalAssets.TwelveMonths > 0]

        sorted_filter: List[Fundamental] = sorted(filtered, 
                                                key=self.fundamental_sorting_key, 
                                                reverse=True)[:self.fundamental_count]

        # Warmup price rolling windows.
        for f in sorted_filter:
            if f.Symbol in self.symbol_data:
                continue
            
            self.symbol_data[f.Symbol] = SymbolData(f.Symbol, self.months_in_year, self.total_assets_history_period)
            history: DataFrame = self.History(f.Symbol, self.months_in_year * self.days_in_month, Resolution.Daily)
            if history.empty:
                self.Log(f"Not enough data for {f.Symbol} yet.")
                continue
            closes: Series = history.loc[f.Symbol].close
            
            # Find monthly closes.
            for index, time_close in enumerate(closes.iteritems()):
                # index out of bounds check.
                if index + 1 < len(closes.keys()):
                    date_month = time_close[0].date().month
                    next_date_month = closes.keys()[index + 1].month
                
                    # Find last day of month.
                    if date_month != next_date_month:
                        self.symbol_data[f.Symbol].update_price(time_close[1])
            
        ready_securities: list[Fundamental] = [x for x in sorted_filter if self.symbol_data[x.Symbol].price_is_ready()]

        # Asset growth calc.
        asset_growth: dict[Symbol, float] = {}
        for security in ready_securities:
            if self.symbol_data[security.Symbol].asset_data_is_ready():
                asset_growth[security.Symbol] = self.symbol_data[security.Symbol].asset_growth()
                
            self.symbol_data[security.Symbol].update_assets(security.FinancialStatements.BalanceSheet.TotalAssets.TwelveMonths)
        
        sorted_by_growth: list[tuple[Symbol, float]] = sorted(asset_growth.items(), key=lambda x: x[1], reverse=True)
        decile: int = int(len(sorted_by_growth) / self.decile)
        top_by_growth: list[Symbol] = [x[0] for x in sorted_by_growth][:decile]
        
        performance: dict[Symbol, float] = {x: self.symbol_data[x].performance() for x in top_by_growth}
        sorted_by_performance: list[tuple[Symbol, float]] = sorted(performance.items(), key=lambda x: x[1], reverse=True)
        quintile = int(len(sorted_by_performance) / self.quintile)
        self.long_symbols = [x[0] for x in sorted_by_performance][:quintile]
        self.short_symbols = [x[0] for x in sorted_by_performance][-quintile:]
        
        return self.long_symbols + self.short_symbols
        
    def OnSecuritiesChanged(self, changes: SecurityChanges) -> None:
        for security in changes.AddedSecurities:
            security.SetFeeModel(CustomFeeModel())

    def OnData(self, slice: Slice) -> None:
        if not self.selection_flag:
            return
        self.selection_flag = False
        
        # Trade execution.
        targets: List[PortfolioTarget] = []
        for i, portfolio in enumerate([self.long_symbols, self.short_symbols]):
            for symbol in portfolio:
                if slice.ContainsKey(symbol) and slice[symbol] is not None:
                    targets.append(PortfolioTarget(symbol, ((-1) ** i) / len(portfolio)))

        self.SetHoldings(targets, True)
        self.long_symbols.clear()
        self.short_symbols.clear()

    def Selection(self) -> None:
        # Exclude January trading.
        if self.Time.month != self.excluded_month:
            self.selection_flag = True
        else:
            self.Liquidate()

class SymbolData():
    def __init__(self, symbol: Symbol, period: int, total_assets_history_period: int) -> None:
        self.Symbol: Symbol = symbol
        self.Price: RollingWindow = RollingWindow[float](period)
        self.TotalAssets: RollingWindow = RollingWindow[float](total_assets_history_period)
    
    def update_price(self, value) -> None:
        self.Price.Add(value)
    
    def update_assets(self, assets_value) -> None:
        self.TotalAssets.Add(assets_value)
    
    def asset_data_is_ready(self) -> bool:
        return self.TotalAssets.IsReady
    
    def asset_growth(self) -> float:
        asset_values: list[float] = [x for x in self.TotalAssets]
        return (asset_values[0] - asset_values[1]) / asset_values[1]
    
    def price_is_ready(self) -> bool:
        return self.Price.IsReady
        
    # Performance, one month skipped.
    def performance(self, values_to_skip: int = 1) -> float:
        closes: list[float] = [x for x in self.Price][values_to_skip:]
        return (closes[0] / closes[-1] - 1)

# Custom fee model
class CustomFeeModel(FeeModel):
    def GetOrderFee(self, parameters: OrderFeeParameters) -> OrderFee:
        fee: float = parameters.Security.Price * parameters.Order.AbsoluteQuantity * 0.00005
        return OrderFee(CashAmount(fee, "USD"))

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