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合理价格买入高质量

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学术论文

股价是否反映公司基本面？大样本全球实证分析

作者Fabio Pulcini

机构

University of Rome Tor Vergata
University of Rome III

论文链接https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4136728

导读

投资标的：SPY、BIL。再平衡：每月。Universe: SPY, BIL. Parameters: rebalance=monthly.

策略概要

该策略投资于Refinitiv Eikon Datastream覆盖的25国非金融公司。用盈利、增长、风险、流动性与公司治理计算质量分数，并在六年历史窗口内标准化为z分数；价格分数由P/B同样标准化。最终Q-P分数为质量减价格。买入Q-P最高十分位、卖出最低十分位。策略等权，每年再平衡。

经济逻辑

高质量股票盈利、稳健且成长，反映强基本面。质量与价格结合可排除高估或低质量股票，并改善风险调整收益。质量与价格负相关增强分散，降低波动而不牺牲预期收益。

入场与出场

入场

用 20 日窗口计算 z 分数。当 z ≤ -1（超卖）时买入 SPY, BIL 中的该标的。

出场

z 回升到 ≥ 0 时平仓，让价格向局部均值回归。

所需行情数据

需要 SPY, BIL 至少 25 根复权收盘价，才能形成第一个有效信号。ETF 仅交易日有行情。实验室通过 backtest.data.load_daily_prices 读取 Yahoo Finance。

标的

SPY, BIL

频率

每年 · 日频复权收盘价；信号按月再平衡（用当月最后一个有效交易日）

所需历史

每个标的至少 25 根交易日 K 线（约 2 个交易月），外加数根缓冲才能发出第一个信号。

字段

复权收盘价（Adj Close / auto_adjust Close）
交易日日期索引

凭证

回测与实验室：无需密钥
实盘下单才需要券商 / 交易所 API

API 与数据源

Quant Buffet 数据 API

实验室用 load_daily_prices 拉取 ASSETS 的复权收盘价面板，磁盘缓存后回测可复现。

提供方: backtest.data.load_daily_prices
鉴权: 回测无需密钥
接口: load_daily_prices(ASSETS, start="2000-01-01")

API / docs → /zh/docs/data-api

Yahoo Finance（yfinance）

美股 / ETF 复权 OHLCV，免费研究接口，有速率限制。

提供方: yfinance → Yahoo Finance
鉴权: 公开历史无需密钥
接口: Ticker.history / yf.download(auto_adjust=True)

API / docs → github.com/ranaroussi/yfinance

Onsite backtest IDE

Quant Buffet 原生回测 IDE

Edit and run Quant Buffet Python for 合理价格买入高质量 in the browser. Results update live with equity, drawdown, and metrics charts. Allowed: backtest.data, backtest.engine, backtest.metrics, numpy, pandas. Define ASSETS and make_on_day(prices). Shortcut: Ctrl+Enter. API docs →

IDE · 44 lines

"""
Quant Buffet interactive lab — 合理价格买入高质量
Allowed: backtest.data / backtest.engine / backtest.metrics, numpy, pandas.
Required: a module-level ASSETS list, and def make_on_day(prices) returning (on_day, ready)
"""
from __future__ import annotations

import numpy as np
import pandas as pd

from backtest.data import load_daily_prices
from backtest.engine import EngineConfig, PortfolioEngine
from backtest.metrics import compute_metrics

ASSETS = ['SPY', 'BIL']
LOOKBACK = 20
ENTRY_Z = -1.0
EXIT_Z = 0.0

def make_on_day(prices: pd.DataFrame):
    cols = [c for c in ASSETS if c in prices.columns]
    mu = prices[cols].rolling(LOOKBACK, min_periods=LOOKBACK).mean()
    sd = prices[cols].rolling(LOOKBACK, min_periods=LOOKBACK).std(ddof=0)
    z = (prices[cols] - mu) / sd.replace(0, np.nan)
    held = {s: False for s in cols}

    def on_day(engine: PortfolioEngine, dt: pd.Timestamp) -> None:
        long = []
        for s in cols:
            zv = z.at[dt, s]
            if pd.isna(zv):
                continue
            if not held[s] and zv <= ENTRY_Z:
                held[s] = True
            elif held[s] and zv >= EXIT_Z:
                held[s] = False
            if held[s]:
                long.append(s)
        w = {} if not long else {s: 1.0 / len(long) for s in long}
        engine.set_target_weights(dt, w)

    ready = z.dropna(how="all").index.min() if z.notna().any().any() else None
    return on_day, ready

"""
Quant Buffet interactive lab — 合理价格买入高质量
Allowed: backtest.data / backtest.engine / backtest.metrics, numpy, pandas.
Required: a module-level ASSETS list, and def make_on_day(prices) returning (on_day, ready)
"""
from __future__ import annotations

import numpy as np
import pandas as pd

from backtest.data import load_daily_prices
from backtest.engine import EngineConfig, PortfolioEngine
from backtest.metrics import compute_metrics

ASSETS = ['SPY', 'BIL']
LOOKBACK = 20
ENTRY_Z = -1.0
EXIT_Z = 0.0

def make_on_day(prices: pd.DataFrame):
    cols = [c for c in ASSETS if c in prices.columns]
    mu = prices[cols].rolling(LOOKBACK, min_periods=LOOKBACK).mean()
    sd = prices[cols].rolling(LOOKBACK, min_periods=LOOKBACK).std(ddof=0)
    z = (prices[cols] - mu) / sd.replace(0, np.nan)
    held = {s: False for s in cols}

def on_day(engine: PortfolioEngine, dt: pd.Timestamp) -> None:
        long = []
        for s in cols:
            zv = z.at[dt, s]
            if pd.isna(zv):
                continue
            if not held[s] and zv <= ENTRY_Z:
                held[s] = True
            elif held[s] and zv >= EXIT_Z:
                held[s] = False
            if held[s]:
                long.append(s)
        w = {} if not long else {s: 1.0 / len(long) for s in long}
        engine.set_target_weights(dt, w)

ready = z.dropna(how="all").index.min() if z.notna().any().any() else None
    return on_day, ready

Quant Buffet syntax cheat sheet (copy / insert)

Paste these fragments into the editor. The sandbox rejects QuantConnect, os, and network libraries.

Required imports

Only these libraries are allowed in the sandbox.

from __future__ import annotations

import numpy as np
import pandas as pd

from backtest.data import load_daily_prices
from backtest.engine import EngineConfig, PortfolioEngine
from backtest.metrics import compute_metrics

ASSETS list (whitelisted ETFs)

Module-level list. Tickers must be in the Quant Buffet whitelist.

ASSETS = ["SPY", "QQQ", "TLT", "GLD", "BIL"]

make_on_day contract

Must return (on_day, ready). on_day calls engine.set_target_weights.

def make_on_day(prices: pd.DataFrame):
    cols = [c for c in ASSETS if c in prices.columns]
    sma = prices[cols].rolling(200, min_periods=200).mean()
    state = {"last": None}

    def on_day(engine: PortfolioEngine, dt: pd.Timestamp) -> None:
        if sma.loc[dt].isna().all():
            return
        key = (dt.year, dt.month)
        if state["last"] == key:
            return
        state["last"] = key
        long = [
            s for s in cols
            if pd.notna(prices.at[dt, s]) and pd.notna(sma.at[dt, s])
            and prices.at[dt, s] > sma.at[dt, s]
        ]
        weights = {} if not long else {s: 1.0 / len(long) for s in long}
        engine.set_target_weights(dt, weights)

    ready = sma.dropna(how="all").index.min() if sma.notna().any().any() else None
    return on_day, ready

Set target weights

Weights should sum to about 1.0. Empty dict = 100% cash.

engine.set_target_weights(dt, {"SPY": 0.60, "BIL": 0.40})

Live backtest performance

CAGR

1.44%

Sharpe

0.17

Max DD

-36.97%

Vol

14.04%

Sortino

0.26

Beta

0.55

Up days

47%

Run the backtest to populate charts.

Order records

Run the backtest to load every order fill alongside performance.

Export to your platform

Transform Quant Buffet lab code (ASSETS + make_on_day / PortfolioEngine) into native classes for a third-party IDE — then copy and paste.

Target platform

Run in: QuantConnect Cloud or LEAN CLI · QCAlgorithm with Equity securities and monthly rebalance.

Detected pattern: Mean reversionAssets: SPY, BIL

# Generated from Quant Buffet → QuantConnect LEAN
# Strategy: 合理价格买入高质量
# Detected pattern: Mean reversion
# Source uses Quant Buffet lab APIs (ASSETS + make_on_day / PortfolioEngine).
# Review fees, data, and risk before live trading — educational export only.

from AlgorithmImports import *


class QuantBuffetExport(QCAlgorithm):
    def Initialize(self):
        self.SetStartDate(2010, 1, 1)
        self.SetCash(100000)
        tickers = ["SPY", "BIL"]
        self.symbols = []
        for t in tickers:
            if "-" in t:  # crypto proxy e.g. BTC-USD
                self.symbols.append(self.AddCrypto(t.replace("-USD", ""), Resolution.Daily).Symbol)
            else:
                self.symbols.append(self.AddEquity(t, Resolution.Daily).Symbol)
        self.Schedule.On(
            self.DateRules.MonthStart(self.symbols[0]),
            self.TimeRules.AfterMarketOpen(self.symbols[0], 30),
            self.Rebalance,
        )
        # Logic: Buy when return z-score < -1 over 20 days.

    def Rebalance(self):
        import numpy as np
        picks = []
        for symbol in self.symbols:
            hist = self.History(symbol, 20 + 5, Resolution.Daily)
            if hist.empty: continue
            close = hist["close"]
            if hasattr(close, "unstack"):
                close = close.unstack(level=0).iloc[:, 0]
            rets = close.pct_change().dropna()
            if len(rets) < 20: continue
            window = rets.iloc[-20:]
            z = (window.iloc[-1] - window.mean()) / (window.std() or 1e-9)
            if z < -1:
                picks.append(symbol)
        w = 1.0 / len(picks) if picks else 0.0
        for symbol in self.symbols:
            self.SetHoldings(symbol, w if symbol in picks else 0.0)

导出代码使用目标平台的原生类与库。请在第三方 IDE 中安装依赖后运行；实盘前请自行验证。