Andrew Ang

Asymmetric Correlations of Equity Portfolios

Correlations between US stocks and the aggregate US market are much greater for downside moves, especially for extreme downside moves, than for upside moves. We develop a new statistic for measuring, comparing and testing asymmetries in conditional correlations. Conditional on the downside, correlations in the data differ from the conditional correlations implied by a normal distribution by 11.6%. We find that conditional asymmetric correlations are fundamentally different from other measures of asymmetry like skewness and co-skewness. We find that small stocks, value stocks and past loser stocks have more asymmetric movements. Controlling for size, we find that stocks with lower betas exhibit greater correlation asymmetries and we find no relationship between leverage and correlation asymmetries. Correlation asymmetries in the data reject the null of multivariate normal distributions at daily, weekly and monthly frequencies. However, several empirical models with greater flexibility, particularly regime-switching models, perform much better at capturing correlation asymmetries.

Regime Switches in Interest Rates

Regime-switching models are well suited to capture the non-linearities in interest rates. This paper examines the econometric performance of regime-switching models for interest rate data from the US, Germany and the UK. There is strong evidence supporting the presence of regime switches but univariate models are unlikely to yield consistent estimates of the model parameters. Regime-switching models incorporating international short rate and term spread information forecast better, match sample moments better, and classify regimes better than univariate models. We show that the regimes in interest rates correspond reasonably well with business cycles, at least in the US. This may explain why regime-switching models forecast interest rates better than single regime models. Finally, the non-linear interest rate dynamics implied by regime-switching models have potentially important implications for the macroeconomic literature documenting the effects of monetary policy shocks on economic aggregates. Moreover, the implied volatility and drift functions are rich enough to resemble those recently estimated using non-parametric techniques.

What does the yield curve tell us about GDP growth

A lot, including a few things you may not expect. Previous studies find that the term spread forecasts GDP but these regressions are unconstrained and do not model regressor endogeneity. We build a dynamic model for GDP growth and yields that completely characterizes expectations of GDP. The model does not permit arbitrage. Contrary to previous findings, we predict that the short rate has more predictive power than any term spread. We confirm this finding by forecasting GDP out-of-sample. The model also recommends the use of lagged GDP and the longest maturity yield to measure slope. Greater efficiency enables the yield-curve model to produce superior out-of-sample GDP forecasts than unconstrained OLS regressions at all horizons.

No-arbitrage Taylor rules

We estimate Taylor (1993) rules and identify monetary policy shocks using no-arbitrage pricing techniques. Long-term interest rates are risk-adjusted expected values of future short rates and thus provide strong over-identifying restrictions about the policy rule used by the Federal Reserve. The no-arbitrage framework also accommodates backward-looking and forward-looking Taylor rules. We find that inflation and output gap account for over half of the variation of time-varying excess bond returns and most of the movements in the term spread. Taylor rules estimated with no-arbitrage restrictions differ from Taylor rules estimated by OLS, and the resulting monetary policy shocks are somewhat less volatile than their OLS counterparts.

What Does the Yield Curve Tell Us About GDP Growth

A lot, including a few things you may not expect. Previous studies find that the term spread forecasts GDP but these regressions are unconstrained and do not model regressor endogeneity. We build a dynamic model for GDP growth and yields that completely characterizes expectations of GDP. The model does not permit arbitrage. Contrary to previous findings, we predict that the short rate has more predictive power than any term spread. We confirm this finding by forecasting GDP out-of-sample. The model also recommends the use of lagged GDP and the longest maturity yield to measure slope. Greater efficiency enables the yield-curve model to produce superior out-of-sample GDP forecasts than unconstrained OLS at all horizons.

Systemic Sovereign Credit Risk: Lessons from the U.S. and Europe

We study the nature of systemic sovereign credit risk using CDS spreads for the U.S. Treasury, individual U.S. states, and major European countries. Using a multifactor affine framework that allows for both systemic and sovereign-specific credit shocks, we find that there is considerable heterogeneity across U.S. and European issuers in their sensitivity to systemic risk. U.S. and Euro systemic shocks are highly correlated, but there is much less systemic risk among U.S. sovereigns than among European sovereigns. We also find that U.S. and European systemic sovereign risk is strongly related to financial market variables. These results provide strong support for the view that systemic sovereign risk has its roots in financial markets rather than in macroeconomic fundamentals.

Short rate nonlinearities and regime switches

Using non-parametric estimation methods, various authors have shown distinct non-linearities in the drift and volatility function of the US short rate, which are inconsistent with standard affine term structure models. We document how a regime-switching model with state dependent transition probabilities between regimes can replicate the patterns found by the non-parametric studies. To do so, we use data from the UK and Germany in addition to US data and include term spreads in some of our models. We also examine the drift and volatility function of the term spread.

Taxes on Tax-Exempt Bonds

Implicit tax rates priced in the cross section of municipal bonds are approximately two to three times as high as statutory income tax rates, with implicit tax rates close to 100% using retail trades and above 70% for interdealer trades. These implied tax rates can be identified on the cross section of municipal bonds because a portion of secondary market municipal bond trades involve income taxes. After valuing the tax payments, market discount bonds, which carry income tax liabilities, trade at yields around 25 basis points higher than comparable municipal bonds not subject to any taxes. The high sensitivities of municipal bond prices to tax rates can be traced to individual retail traders dominating dealers and other institutions.

A General Affine Earnings Valuation Model

We introduce a methodology, with two applications, that incorporates stochastic interest rates, heteroskedasticity and risk aversion into the residual income model. In the first application, goodwill is an affine (constant plus linear term) function where the constant and linear coefficients are time-varying. Homoskedastic risk gives rise to a constant risk premium, while heteroskedastic risk gives rise to linear state-dependent risk premiums. In the second application, we present a class of models where a non-linear function for the price-to-book ratio can be derived. We show how interest rates, risk, profitability and growth affect the price-to-book ratio.

Build America Bonds

Build America Bonds (BABs) are a new form of municipal financing introduced in 2009. Investors in BAB municipal bonds receive interest payments that are taxable, but issuers receive a subsidy from the U.S. Treasury. The BAB program has succeeded in lowering the cost of funding for state and local governments with BAB issuers obtaining finance 54 basis points lower, on average, compared to issuing regular municipal bonds. For institutional investors, BAB issue yields are 116 bps higher than comparable Treasuries and 88 bps higher than comparable highly rated corporate bonds. For individual investors, BABs represent poor deals compared to regular municipal bonds. Thus, on average the Federal government subsidy disadvantages individual U.S. taxpayers, who are the main holders of municipal bonds, and benefits new entrants in the municipal bond market.