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Submitted
Mulenga, A., M. Faias, P. Mota, and J. P. Pina. "Exchange rate volatility: An asymmetric tale from Mozambique." (Submitted). Abstract

This paper inspects how risk is affected by news sign and size within - depreciation, appreciation, stability - distinct exchange rate trends, and by volatility model choice, taking on various asymmetric Generalized Autoregressive Conditional Heteroskedasticity models to daily Mozambique New Metical against South Africa Rand, MZN/ZAR, exchange rate over January 2010 - December 2014. Our results show that risk measurement
and asymmetry of shocks to volatility depend on exchange rate trend, being that estimating the full sample conceals the actual behavior, and model choice, specifically the degree of nonlinearity and persistence. In particular, we find that when positive/negative news type matches the sign of the exchange rate trend, risk increases by more. Interestingly, this means that in times of appreciation the good news turns out to be bad,
likely because they raise the fear of overvaluation, under monitoring in natural resource producers and exporting countries. The findings contribute to the growing concern on nonlinear economic policy design, exchange rate targeting and surely international trade and investment decisions, where an incorrect assessment exchange rate risk and asymmetry may lead to mispricing of assets, namely options, and eventual underestimation of
measures, as Value at Risk, relevant for Basel agreement.

2021
Costa, S., M. Faias, P. Júdice, and P. Mota. "Panel data modeling of bank deposits." Annals of Finance. 17 (2021): 247-264. AbstractWebsite

Studying the dynamics of deposits is important for three reasons: first, it serves as an important component of liquidity stress testing; second, it is crucial to asset-liability management exercises and the allocation between liquid and illiquid assets; third, it is the support for a liquidity at risk (LaR) methodology.

Current models are based on AR(1) processes that often underestimate liquidity risk. Thus a bank relying on those models may face failure in an event of crisis. We propose a novel approach for modeling deposits, using panel data and a momentum term.

The model enables the simulation of a variety of deposit trajectories, including episodes of financial distress, showing much higher drawdowns and realistic liquidity at risk estimates, as well as density plots that present a wide range of possible values, corresponding to booms and financial crises.

Therefore, this methodology is more suitable for liquidity management at banks, as well as for conducting liquidity stress tests.

2019
Mulenga, A., M. Faias, P. Mota, and J. P. Pina. "What happens when the stock markets are closed?" Electronic Journal of Applied Statistical Analysis. 12.2 (2019): 405-415. AbstractWebsite

The normality of the log-return of stock prices is often assumed by the market players in order to use some useful results, as for instance, the Black-Scholes formula for pricing European options. However, several studies regarding different indexes have shown that the normality assumption of the returns usually fails.
In this paper we analyse the normality assumption for intra-day and inter-day log-returns, comparing opening prices and/or closing prices for a large number of companies quoted in the Nasdaq Composite index. We use the Pearson's Chi-Square, Kolmogorov-Smirnov, Anderson-Darling, Shapiro-Wilks and Jarque-Bera goodness-of-fit tests to study the normality assumption.
We find that the failure rate in the normality assumption for the log-return of stock prices is not the same for intra-day and inter-day prices, is somewhat test dependent and strongly dependent on some extreme price observations.
To the best of our knowledge, this is the first study on the normality assumption for the log-return of stock prices dealing simultaneously with a large number of companies and normality tests, and at the same time considering various scenarios of intra-day, inter-day prices and data trimming.

2016
Faias, Marta, Pedro Mota, Alberto Mulenga, and Joaquim P. Pina. "Asymmetry of ARCH effects and natural resources disease or virtue: Mozambique experience." AIP Conference Proceedings. 1738 (2016). AbstractWebsite

We study the exchange rate behavior, mainly as to the presence of asymmetry in the shocks to conditional variance. Particularly, we investigate if the presence of that asymmetric response is specific to a marked behavior of the currency, appreciation/Dutch disease/depreciation, and if it appears masked when taking long non-homogeneous periods. Taking Mozambique Metical bilateral exchange rate against South Africa Rand, a major trading partner, we identify specific movements in defined sub-periods, where the most recent has the Dutch disease under scrutiny. Our results point out that asymmetry emerges especially when the currency is depreciating, while it is masked when considering larger periods that combine differences in currency behavior.