The global economy experienced a worldwide meltdown of asset markets in the
years 2007–2009. This posed great challenges for asset and portfolio managers.
Many funds such as university endowments, sovereign wealth funds, and pension
funds were overexposed to risky returns and suffered considerable losses. On the
other hand, the long-run upswing in the stock market since 2010, induced by a
monetary policy of quantitative easing in the USA, and later in Europe and Asia,
led to asset price booms and new wealth formation. In both cases quite significant
differences in asset management and wealth accumulation were visible. Our book
aims at dealing with sustainable wealth formation and dynamic decision making.
We have three perspectives in mind.
A first perspective is how wealth formation and the proper management of
financial funds can help to buffer income risk sufficiently and to obtain adequate
risk-free income at a later stage of life. This is an important concern in the current
public debate on asset accumulation and wealth disparity. In whatever institutional
form saving takes place, in mutual funds, public pension funds, corporate pension
funds, or private saving accounts, the generic issue is how much to save and invest
and how to make proper asset allocation decisions.
A second important issue for sustainable wealth accumulation is that many
agents and institutions in financial markets tend to put some constraints on the
accumulation and allocation of assets—following some rules, guidelines and restrictions concerning risk-taking, safeness of investments, as well as social, ethical,
environmental, and climate change aspects. Thus investments are often restricted
to certain risk classes, classes of assets or particular assets. Much investment and
asset allocation decisions are therefore made following behavioral and institutional
rules, responding to some given constraints and guidelines, without necessarily
being optimal in the narrow sense.
A third perspective of sustainable wealth formation is that we want to move more
toward dynamic decision making and dynamic re-balancing of portfolios. Portfolio
decisions are frequently modeled as static decisions problems. Yet, how should the
investors respond to expected future returns, changing return differentials, global or
idiosyncratic risk, change of inflation rates, affecting the real value of their assets,
and so on? In standard literature, the modeling of savings and wealth accumulation
are often separated from asset allocation decisions. We pursue a simultaneous and
dynamic treatment of both savings behavior and portfolio decision making, taking
into account expected returns. Expected returns are evaluated here, using a new
method—harmonic estimations of returns.
In order to solve such dynamic decision problems in portfolio theory and
portfolio practice—solving saving as well as asset accumulation problems
simultaneously—we put forward dynamic programming as a procedure for dynamic
decision making that allows to integrate sustainable wealth accumulation as well as
asset allocation decisions. Although some shortcomings of this procedure exist, a
careful use of it can help to not only undertake dynamic modeling but also aid online
decision making once some pattern of expected returns of different asset classes,
for example estimated through using harmonic estimations, has been recognized.
The book is written in a way that it can be used by researchers and in graduate
classes on financial economics, asset pricing and portfolio theory, finance and
macro, portfolio theory and practice, pension fund theory and management, socially
responsible investment decisions, financial market and wealth disparities, methodology of dynamic portfolio theory, intertemporal asset allocation and households’saving, and applied dynamic programming.
Parts of the book are based on lectures delivered at the University of Bielefeld,
Germany, the University of Technology, Sydney, Australia, The New School for
Social Research, New York City, USA, and University of Economics, Vienna,
Austria, as well as conferences and workshops at the ZEW, Mannheim, Germany.
We are very grateful to our colleagues at those institutions as well as to several
generations of students who took our classes in this area and gave comments on
these lectures in their formative stages. We are also grateful for discussions with
Hans Amman, Lucas Bernard, Raphaele Chappe, Peter Flaschel, Lars Gruene,
Stefan Mittnik, Unra Nyambuu, Eckhard Platen, and James Ramsey.
Individually, many of the chapters of the book have been presented at conferences, workshops, and seminars throughout the United States, Europe, and
Australia. Many chapters of this book are also based on previous article by the
authors, published with a variety of different coauthors. Each chapter acknowledges
the particular coauthors involved, and a general acknowledgment can be found
below.
In preparing this manuscript, we in particular relied on the help of Tony Bonen
and Uwe Koeller whom we want to thank for extensive assistance in editing this
volume. Willi Semmler wants to thank the Fulbright Foundation for a Fulbright
Professorship at the University of Economics, Vienna, in the Winter Term 2011, as
well as the German Research Foundation for financial support.