skfolio is a Python library for portfolio optimization built on top of scikit-learn. It offers a unified interface and tools compatible with scikit-learn to build, fine-tune, and cross-validate portfolio models.

It is distributed under the open source 3-Clause BSD license.

.. image:: https://raw.githubusercontent.com/skfolio/skfolio/master/docs/_static/expo.jpg :target: https://skfolio.org/auto_examples/ :alt: examples

Important links


- Documentation: https://skfolio.org/
- Examples: https://skfolio.org/auto_examples/
- User Guide: https://skfolio.org/user_guide/
- GitHub Repo: https://github.com/skfolio/skfolio/

Installation
~~~~~~~~~~~~

`skfolio` is available on PyPI and can be installed with::

    pip install -U skfolio



Dependencies
~~~~~~~~~~~~

`skfolio` requires:

- python (>= |PythonMinVersion|)
- numpy (>= |NumpyMinVersion|)
- scipy (>= |ScipyMinVersion|)
- pandas (>= |PandasMinVersion|)
- cvxpy (>= |CvxpyMinVersion|)
- scikit-learn (>= |SklearnMinVersion|)
- joblib (>= |JoblibMinVersion|)
- plotly (>= |PlotlyMinVersion|)

Key Concepts
~~~~~~~~~~~~
Since the development of modern portfolio theory by Markowitz (1952), mean-variance
optimization (MVO) has received considerable attention.

Unfortunately, it faces a number of shortcomings, including high sensitivity to the
input parameters (expected returns and covariance), weight concentration, high turnover,
and poor out-of-sample performance.

It is well known that naive allocation (1/N, inverse-vol, etc.) tends to outperform
MVO out-of-sample (DeMiguel, 2007).

Numerous approaches have been developed to alleviate these shortcomings (shrinkage,
additional constraints, regularization, uncertainty set, higher moments, Bayesian
approaches, coherent risk measures, left-tail risk optimization, distributionally robust
optimization, factor model, risk-parity, hierarchical clustering, ensemble methods,
pre-selection, etc.).

With this large number of methods, added to the fact that they can be composed together,
there is a need for a unified framework with a machine learning approach to perform
model selection, validation, and parameter tuning while reducing the risk of data
leakage and overfitting.

This framework is built on scikit-learn's API.

Available models

Portfolio Optimization:
- Naive:
  - Equal-Weighted
  - Inverse-Volatility
  - Random (Dirichlet)
- Convex:
  - Mean-Risk
  - Risk Budgeting
  - Maximum Diversification
  - Distributionally Robust CVaR
- Clustering:
  - Hierarchical Risk Parity
  - Hierarchical Equal Risk Contribution
  - Nested Clusters Optimization
- Ensemble Methods:
  - Stacking Optimization
Expected Returns Estimator:
- Empirical
- Exponentially Weighted
- Equilibrium
- Shrinkage
Covariance Estimator:
- Empirical
- Gerber
- Denoising
- Detoning
- Exponentially Weighted
- Ledoit-Wolf
- Oracle Approximating Shrinkage
- Shrunk Covariance
- Graphical Lasso CV
- Implied Covariance
Distance Estimator:
- Pearson Distance
- Kendall Distance
- Spearman Distance
- Covariance Distance (based on any of the above covariance estimators)
- Distance Correlation
- Variation of Information
Prior Estimator:
- Empirical
- Black & Litterman
- Factor Model
Uncertainty Set Estimator:
- On Expected Returns:
  - Empirical
  - Circular Bootstrap
- On Covariance:
  - Empirical
  - Circular bootstrap
Pre-Selection Transformer:
- Non-Dominated Selection
- Select K Extremes (Best or Worst)
- Drop Highly Correlated Assets
Cross-Validation and Model Selection:
- Compatible with all sklearn methods (KFold, etc.)
- Walk Forward
- Combinatorial Purged Cross-Validation
Hyper-Parameter Tuning:
- Compatible with all sklearn methods (GridSearchCV, RandomizedSearchCV)
Risk Measures:
- Variance
- Semi-Variance
- Mean Absolute Deviation
- First Lower Partial Moment
- CVaR (Conditional Value at Risk)
- EVaR (Entropic Value at Risk)
- Worst Realization
- CDaR (Conditional Drawdown at Risk)
- Maximum Drawdown
- Average Drawdown
- EDaR (Entropic Drawdown at Risk)
- Ulcer Index
- Gini Mean Difference
- Value at Risk
- Drawdown at Risk
- Entropic Risk Measure
- Fourth Central Moment
- Fourth Lower Partial Moment
- Skew
- Kurtosis
Optimization Features:
- Minimize Risk
- Maximize Returns
- Maximize Utility
- Maximize Ratio
- Transaction Costs
- Management Fees
- L1 and L2 Regularization
- Weight Constraints
- Group Constraints
- Budget Constraints
- Tracking Error Constraints
- Turnover Constraints

Quickstart

The code snippets below are designed to introduce the functionality of `skfolio` so you
can start using it quickly. It follows the same API as scikit-learn.

Imports
-------
.. code-block:: python

    from sklearn import set_config
    from sklearn.model_selection import (
        GridSearchCV,
        KFold,
        RandomizedSearchCV,
        train_test_split,
    )
    from sklearn.pipeline import Pipeline
    from scipy.stats import loguniform

    from skfolio import RatioMeasure, RiskMeasure
    from skfolio.datasets import load_factors_dataset, load_sp500_dataset
    from skfolio.model_selection import (
        CombinatorialPurgedCV,
        WalkForward,
        cross_val_predict,
    )
    from skfolio.moments import (
        DenoiseCovariance,
        DetoneCovariance,
        EWMu,
        GerberCovariance,
        ShrunkMu,
    )
    from skfolio.optimization import (
        MeanRisk,
        NestedClustersOptimization,
        ObjectiveFunction,
        RiskBudgeting,
    )
    from skfolio.pre_selection import SelectKExtremes
    from skfolio.preprocessing import prices_to_returns
    from skfolio.prior import BlackLitterman, EmpiricalPrior, FactorModel
    from skfolio.uncertainty_set import BootstrapMuUncertaintySet

Load Dataset
------------
.. code-block:: python

    prices = load_sp500_dataset()

Train/Test split
----------------
.. code-block:: python

    X = prices_to_returns(prices)
    X_train, X_test = train_test_split(X, test_size=0.33, shuffle=False)


Minimum Variance
----------------
.. code-block:: python

    model = MeanRisk()

Fit on Training Set
-------------------
.. code-block:: python

    model.fit(X_train)

    print(model.weights_)

Predict on Test Set
-------------------
.. code-block:: python

    portfolio = model.predict(X_test)

    print(portfolio.annualized_sharpe_ratio)
    print(portfolio.summary())



Maximum Sortino Ratio
---------------------
.. code-block:: python

    model = MeanRisk(
        objective_function=ObjectiveFunction.MAXIMIZE_RATIO,
        risk_measure=RiskMeasure.SEMI_VARIANCE,
    )


Denoised Covariance & Shrunk Expected Returns
---------------------------------------------
.. code-block:: python

    model = MeanRisk(
        objective_function=ObjectiveFunction.MAXIMIZE_RATIO,
        prior_estimator=EmpiricalPrior(
            mu_estimator=ShrunkMu(), covariance_estimator=DenoiseCovariance()
        ),
    )

Uncertainty Set on Expected Returns
-----------------------------------
.. code-block:: python

    model = MeanRisk(
        objective_function=ObjectiveFunction.MAXIMIZE_RATIO,
        mu_uncertainty_set_estimator=BootstrapMuUncertaintySet(),
    )


Weight Constraints & Transaction Costs
--------------------------------------
.. code-block:: python

    model = MeanRisk(
        min_weights={"AAPL": 0.10, "JPM": 0.05},
        max_weights=0.8,
        transaction_costs={"AAPL": 0.0001, "RRC": 0.0002},
        groups=[
            ["Equity"] * 3 + ["Fund"] * 5 + ["Bond"] * 12,
            ["US"] * 2 + ["Europe"] * 8 + ["Japan"] * 10,
        ],
        linear_constraints=[
            "Equity <= 0.5 * Bond",
            "US >= 0.1",
            "Europe >= 0.5 * Fund",
            "Japan <= 1",
        ],
    )
    model.fit(X_train)


Risk Parity on CVaR
-------------------
.. code-block:: python

    model = RiskBudgeting(risk_measure=RiskMeasure.CVAR)

Risk Parity & Gerber Covariance
-------------------------------
.. code-block:: python

    model = RiskBudgeting(
        prior_estimator=EmpiricalPrior(covariance_estimator=GerberCovariance())
    )

Nested Cluster Optimization with Cross-Validation and Parallelization
---------------------------------------------------------------------
.. code-block:: python

    model = NestedClustersOptimization(
        inner_estimator=MeanRisk(risk_measure=RiskMeasure.CVAR),
        outer_estimator=RiskBudgeting(risk_measure=RiskMeasure.VARIANCE),
        cv=KFold(),
        n_jobs=-1,
    )

Randomized Search of the L2 Norm
--------------------------------
.. code-block:: python

    randomized_search = RandomizedSearchCV(
        estimator=MeanRisk(),
        cv=WalkForward(train_size=252, test_size=60),
        param_distributions={
            "l2_coef": loguniform(1e-3, 1e-1),
        },
    )
    randomized_search.fit(X_train)

    best_model = randomized_search.best_estimator_

    print(best_model.weights_)


Grid Search on Embedded Parameters
----------------------------------
.. code-block:: python

    model = MeanRisk(
        objective_function=ObjectiveFunction.MAXIMIZE_RATIO,
        risk_measure=RiskMeasure.VARIANCE,
        prior_estimator=EmpiricalPrior(mu_estimator=EWMu(alpha=0.2)),
    )

    print(model.get_params(deep=True))

    gs = GridSearchCV(
        estimator=model,
        cv=KFold(n_splits=5, shuffle=False),
        n_jobs=-1,
        param_grid={
            "risk_measure": [
                RiskMeasure.VARIANCE,
                RiskMeasure.CVAR,
                RiskMeasure.VARIANCE.CDAR,
            ],
            "prior_estimator__mu_estimator__alpha": [0.05, 0.1, 0.2, 0.5],
        },
    )
    gs.fit(X)

    best_model = gs.best_estimator_

    print(best_model.weights_)


Black & Litterman Model
-----------------------
.. code-block:: python

    views = ["AAPL - BBY == 0.03 ", "CVX - KO == 0.04", "MSFT == 0.06 "]
    model = MeanRisk(
        objective_function=ObjectiveFunction.MAXIMIZE_RATIO,
        prior_estimator=BlackLitterman(views=views),
    )

Factor Model
------------
.. code-block:: python

    factor_prices = load_factors_dataset()

    X, y = prices_to_returns(prices, factor_prices)
    X_train, X_test, y_train, y_test = train_test_split(X, y, test_size=0.33, shuffle=False)

    model = MeanRisk(prior_estimator=FactorModel())
    model.fit(X_train, y_train)

    print(model.weights_)

    portfolio = model.predict(X_test)

    print(portfolio.calmar_ratio)
    print(portfolio.summary())


Factor Model & Covariance Detoning
----------------------------------
.. code-block:: python

    model = MeanRisk(
        prior_estimator=FactorModel(
            factor_prior_estimator=EmpiricalPrior(covariance_estimator=DetoneCovariance())
        )
    )

Black & Litterman Factor Model
------------------------------
.. code-block:: python

    factor_views = ["MTUM - QUAL == 0.03 ", "VLUE == 0.06"]
    model = MeanRisk(
        objective_function=ObjectiveFunction.MAXIMIZE_RATIO,
        prior_estimator=FactorModel(
            factor_prior_estimator=BlackLitterman(views=factor_views),
        ),
    )

Pre-Selection Pipeline
----------------------
.. code-block:: python

    set_config(transform_output="pandas")
    model = Pipeline(
        [
            ("pre_selection", SelectKExtremes(k=10, highest=True)),
            ("optimization", MeanRisk()),
        ]
    )
    model.fit(X_train)

    portfolio = model.predict(X_test)




K-fold Cross-Validation
-----------------------
.. code-block:: python

    model = MeanRisk()
    mmp = cross_val_predict(model, X_test, cv=KFold(n_splits=5))
    # mmp is the predicted MultiPeriodPortfolio object composed of 5 Portfolios (1 per testing fold)

    mmp.plot_cumulative_returns()
    print(mmp.summary())


Combinatorial Purged Cross-Validation
-------------------------------------
.. code-block:: python

    model = MeanRisk()

    cv = CombinatorialPurgedCV(n_folds=10, n_test_folds=2)

    print(cv.get_summary(X_train))

    population = cross_val_predict(model, X_train, cv=cv)

    population.plot_distribution(
        measure_list=[RatioMeasure.SHARPE_RATIO, RatioMeasure.SORTINO_RATIO]
    )
    population.plot_cumulative_returns()
    print(population.summary())


Recognition

We would like to thank all contributors behind our direct dependencies, such as scikit-learn and cvxpy, but also the contributors of the following resources that were a source of inspiration:

* PyPortfolioOpt
* Riskfolio-Lib
* scikit-portfolio
* microprediction
* statsmodels
* rsome
* gautier.marti.ai

Citation


If you use `skfolio` in a scientific publication, we would appreciate citations:

Bibtex entry::

    @misc{skfolio,
      author = {Delatte, Hugo and Nicolini, Carlo},
      title = {skfolio},
      year  = {2023},
      url   = {https://github.com/skfolio/skfolio}
    }

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