93 research outputs found
Factorising equity returns in an emerging market through exogenous shocks and capital flows
A technique from stochastic portfolio theory [Fernholz, 1998] is applied to
analyse equity returns of Small, Mid and Large cap portfolios in an emerging
market through periods of growth and regional crises, up to the onset of the
global financial crisis. In particular, we factorize portfolios in the South
African market in terms of distribution of capital, change of stock ranks in
portfolios, and the effect due to dividends for the period Nov 1994 to May
2007. We discuss the results in the context of broader economic thinking to
consider capital flows as risk factors, turning around more established
approaches which use macroeconomic and socio-economic conditions to explain
Foreign Direct Investment (into the economy) and Net Portfolio Investment (into
equity and bond markets).Comment: 27 pages, 12 figure
High-speed detection of emergent market clustering via an unsupervised parallel genetic algorithm
We implement a master-slave parallel genetic algorithm (PGA) with a bespoke
log-likelihood fitness function to identify emergent clusters within price
evolutions. We use graphics processing units (GPUs) to implement a PGA and
visualise the results using disjoint minimal spanning trees (MSTs). We
demonstrate that our GPU PGA, implemented on a commercially available general
purpose GPU, is able to recover stock clusters in sub-second speed, based on a
subset of stocks in the South African market. This represents a pragmatic
choice for low-cost, scalable parallel computing and is significantly faster
than a prototype serial implementation in an optimised C-based
fourth-generation programming language, although the results are not directly
comparable due to compiler differences. Combined with fast online intraday
correlation matrix estimation from high frequency data for cluster
identification, the proposed implementation offers cost-effective,
near-real-time risk assessment for financial practitioners.Comment: 10 pages, 5 figures, 4 tables, More thorough discussion of
implementatio
Essential Spectra of Linear Relations
Five essential spectra of linear relations are defined in terms of
semi-Fredholm properties and the index. Basic properties of these sets are
established and the perturbation theory for semi-Fredholm relations is then
applied to verify a generalisation of Weyl's theorem for single-valued
operators. We conclude with a spectral mapping theorem.Comment: 11 page
Multivalued semi-Fredholm operators in normed linear spaces
Bibliography: leaves 176-182.Certain properties associated with these classes are stable under small perturbation, i.e. stable under additive perturbation by continuous operators whose norms are less than the minimum modulus of the relation being perturbed, and are also stable under perturbation by compact, strictly singular or strictly cosingular operators. In this work we continue the study of these classes and introduce the classes of α-Atkinson and β-Atkinson relations. These are subclasses of upper and lower semi-Fredholm relations respectively, having generalised inverses and defined in terms of the existence of continuous projections onto their ranges and nullspaces
An analysis of Cross-correlations in South African Market data
We apply random matrix theory to compare correlation matrix estimators C
obtained from emerging market data. The correlation matrices are constructed
from 10 years of daily data for stocks listed on the Johannesburg Stock
Exchange (JSE) from January 1993 to December 2002. We test the spectral
properties of C against random matrix predictions and find some agreement
between the distributions of eigenvalues, nearest neighbour spacings,
distributions of eigenvector components and the inverse participation ratios
for eigenvectors. We show that interpolating both missing data and illiquid
trading days with a zero-order hold increases agreement with RMT predictions.
For the more realistic estimation of correlations in an emerging market, we
suggest a pairwise measured-data correlation matrix. For the data set used,
this approach suggests greater temporal stability for the leading eigenvectors.
An interpretation of eigenvectors in terms of trading strategies is given in
lieu of classification by economic sectors.Comment: 19 pages, 15 figures, additional figures, discussion and reference
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