On-Line Portfolio Selection Using Multiplicative Updates

We present an on-line investment algorithm that achieves almost the same wealth as the best constant-rebalanced portfolio determined in hindsight from the actual market outcomes. The algorithm employs a multiplicative update rule derived using a framework introduced by Kivinen and Warmuth. Our algorithm is very simple to implement and requires only constant storage and computing time per stock in each trading period. We tested the performance of our algorithm on real stock data from the New York Stock Exchange accumulated during a 22-year period. On these data, our algorithm clearly outperforms the best single stock as well as Cover's universal portfolio selection algorithm. We also present results for the situation in which the investor has access to additional "side information."     

Wolf in Sheep's Clothing: The Active Investment Strategies behind Index Performance

This paper argues that the commonly used market indices imply forms of active investment management in disguise. The selection and rebalancing rules make these indices highly exclusive and dynamic regarding their underlying components and significantly bias their performance. Any passive investment tracking these indices turns into an active strategy characterised by market timing and state‐dependent performance. Evidence is provided that exclusive indices outperform (underperform) more inclusive peer indices in upward (downward) markets. The constitution and maintenance rules of exclusive indices correspond to a set of active trading and investment rules similar to momentum strategies.     

全球经济再平衡下的贸易保护主义对中国出口的挑战

全球贸易在2009年经历了22%的降幅以后,经济逐渐呈现回升态势,但是由于失业率上升,政治压力和社会问题接踵而至,越来越多国家以"经济安全"和保护本国虚弱产业为由加强政府对经济的干预,贸易保护主义日渐盛行。在未来相当一段时期内,随着中国商品结构的升级和对外贸易的进一步扩大,国际对华贸易保护主义案例在数量上将保持上升趋势,涉及的领域将继续扩大,对华贸易保护主义的形式将趋于多样化。对此,我们需要保持清醒的认识,及早未雨绸缪。     

再平衡推动中国经济进入新上升周期——2009—2010年中国经济形势分析和展望

2009年在保增长成功的同时经济失衡再加剧。再平衡将成为2010年宏观政策的核心。在世界经济好转和再平衡政策的推动下，2010年中国经济将迎来全面复苏。     

Rebalancing China's Economy: Domestic and International Implications

This paper considers interactions between China's domestic and external imbalances and their global implications. We present scenarios detailing how a rebalancing of China's growth pattern from investment‐driven growth towards more consumption‐driven growth may occur in practice. Using input–output tables for 2012, we illustrate the knife‐edged nature of Chinese rebalancing, the linkages between expenditure‐side and production‐side rebalancing, and how an internal rebalancing could exacerbate external imbalances. A policy implication for China is that for rebalancing to be fast, consumption must be exceptionally resilient and the efficiency of investment must increase sharply. If rebalancing is too slow, the capital‐to‐output ratio will rise to potentially unsustainable levels and consumption will fail to attain levels of contemporary upper middle‐income economies by 2030. Global input–output tables (1995–2011) suggest that the patterns of Chinese rebalancing considered in our scenarios may generate substantial headwinds for exports to China by its trading partners.     

Banking on the FED: QE1-2-3 and the Rebalancing of the Global Economy

Growing income inequality in most countries in the 1990s and 2000s led to a global shortfall between supply and demand. The US economy bridged this shortfall domestically and globally by blowing successive equity market and housing bubbles, but these produced ever more severe financial crises. Rebalancing after the 2008 crisis required trade surplus countries to expand their non-traded sectors, but rebalancing is never immaculate. Instead, the Federal Reserve Bank's three rounds of Large-Scale Asset Purchases, or quantitative easing, shifted investment flows towards some developed and developing economies. As a matter of accounting, capital inflows led to shrinking trade surpluses in those countries. However, their relatively undeveloped securities markets mean that rebalancing largely occurred through rising housing prices, mirroring the same unsustainable phenomenon the USA experienced in the 2000s. In effect, the USA shifted part of its unsustainably large non-traded sector back to trade surplus countries by causing the real-estate part of the non-traded sector in surplus countries to expand. However, this is not a sustainable solution to global trade and financial imbalances in the long run, and risks producing the same kind of crises the USA experienced in 2008.     

Institutional arrangements and price rebalancing: empirical evidence from the United States and Europe

This paper explores the rebalancing of prices for voice service in the United States (US) and the European Union (EU) from conceptual and empirical perspectives. We determine the overall cost and structure of a standardized basket of residential and business services. Our data indicate that during the 1994–2000 period the degree of rate rebalancing was significantly higher in the EU than in the US. While the developments at the level of EU Member States are more heterogeneous and the process of rate rebalancing is not completed, these findings correspond to the predictions derived from our comparative institutional analysis.     

Universal Portfolios

We exhibit an algorithm for portfolio selection that asymptotically outperforms the best stock in the market. Let x_i= (x_i, x_i2,…, x_im)^t denote the performance of the stock market on day i, where x_ii is the factor by which the jth stock increases on day i. Let b_i= (_bi1 b_i2, b_im)^t, b;_ij? 0, b_ij= 1, denote the proportion b_ij of wealth invested in the j th stock on day i. Then S_n= II_iⁿ= bi^tx_i is the factor by which wealth is increased in n trading days. Consider as a goal the wealth S_n*= max_b II_iⁿ=₁ b^tx_i that can be achieved by the best constant rebalanced portfolio chosen after the stock outcomes are revealed. It can be shown that Sn * exceeds the best stock, the Dow Jones average, and the value line index at time n. In fact, S_n* usually exceeds these quantities by an exponential factor. Let x₁, x₂, be an arbitrary sequence of market vectors. It will be shown that the nonanticipating sequence of portfolios db yields wealth such that , for every bounded sequence x₁, x₂…, and, under mild conditions, achieve where J, is an (m - 1) x (m - I) sensitivity matrix. Thus this portfolio strategy has the same exponential rate of growth as the apparently unachievable S*_n.