Dynamic competition with network externalities: how history matters

We consider dynamic competition among platforms in a market with network externalities. A platform that dominated the market in the previous period becomes “focal” in the current period, in that agents play the equilibrium in which they join the focal platform whenever such equilibrium exists. Yet when faced with higher-quality competition, can a low-quality platform remain focal? In the finite-horizon case, the unique equilibrium is efficient for “patient” platforms; with an infinite time horizon, however, there are multiple equilibria where either the low- or high-quality platform dominates. If qualities are stochastic, the platform with a better average quality wins with a higher probability, even when its realized quality is lower, and this probability increases as platforms become more patient. Hence, social welfare may decline as platforms become more forward looking.     

Pricing and commitment by two‐sided platforms

I study pricing and commitment by platforms in two‐sided markets with the following characteristics: (i) platforms are essential bottleneck inputs for buyers and sellers transacting with each other; (ii) sellers arrive before buyers; and (iii) platforms can charge both fixed fees and variable fees (royalties). I show that a monopoly platform may prefer not to commit to the price it will charge buyers at the same time it announces its seller price if it faces unfavorable seller expectations. With competing platforms, commitment makes the existence of an exclusive equilibrium (in which sellers register with only one platform) less likely, but it has no impact on multi‐homing equilibria (in which sellers support both platforms) whenever these exist.     

Textual sentiment of comments and collapse of P2P platforms: Evidence from China's P2P market

Textual sentiment affects the investment activities of investors in traditional financial markets. Peer-to-Peer (P2P) lending market, as one of the emerging and active Internet financial markets, has recently received considerable attention from academia. However, few related studies are available. This work examines the relationship between the textual sentiment derived from investors’ comments on P2P platforms and probability of platform collapse. We collect comments from an authoritative Chinese third-party P2P lending consulting platform and use a weakly supervised convolutional neural network to calculate the textual sentiment of each comment. Empirical results show that the extracted textual sentiment has a significant influence on a P2P platform's collapse. Furthermore, the “agreement” and “disagreement” from other investors of each comment are pivotal in predicting a P2P platform's failure. We find that the textual sentiment of comments regarding P2P platforms from investor communities provide insights into predicting platforms’ collapse in the near future.     

REVISITING MARKET EFFICIENCY: THE STOCK MARKET AS A COMPLEX ADAPTIVE SYSTEM

Well‐functioning financial markets are key to efficient resource allocation in a capitalist economy. While many managers express reservations about the accuracy of stock prices, most academics and practitioners agree that markets are efficient by some reasonable operational criterion. But if standard capital markets theory provides reasonably good predictions under “normal” circumstances, researchers have also discovered a number of “anomalies”—cases where the empirical data appear sharply at odds with the theory. Most notable are the occasional bursts of extreme stock price volatility (including the recent boom‐and‐bust cycle in the NASDAQ) and the limited success of the Capital Asset Pricing Model in accounting for the actual risk‐return behavior of stocks. This article addresses the question of how the market's efficiency arises. The central message is that managers can better understand markets as a complex adaptive system. Such systems start with a “heterogeneous” group of investors, whose interaction leads to “self‐organization” into groups with different investment styles. In contrast to market efficiency, where “marginal” investors are all assumed to be rational and well‐informed, the interaction of investors with different “decision rules” in a complex adaptive system creates a market that has properties and characteristics distinct from the individuals it comprises. For example, simulations of the behavior of complex adaptive systems suggest that, in most cases, the collective market will prove to be smarter than the average investor. But, on occasion, herding behavior by investors leads to “imbalances”—and, hence, to events like the crash of '87 and the recent plunge in the NASDAQ. In addition to its grounding in more realistic assumptions about the behavior of individual investors, the new model of complex adaptive systems offers predictions that are in some respects more consistent with empirical findings. Most important, the new model accommodates larger‐than‐normal stock price volatility (in statistician's terms, “fat‐tailed” distributions of prices) far more readily than standard efficient market theory. And to the extent that it does a better job of explaining volatility, this new model of investor behavior is likely to have implications for two key areas of corporate financial practice: risk management and investor relations. But even so, the new model leaves one of the main premises of modern finance theory largely intact–that the most reliable basis for valuing a company's stock is its discounted cash flow.     

The failure of Chinese peer-to-peer lending platforms: Finance and politics

We investigate the influence of financial and political factors on peer-to-peer (P2P) platform failures in China's online lending market. Using a competing risk model for platform survival, we show that large platforms, platforms with listed firms as large shareholders, and platforms with better information disclosure were less likely to go bankrupt or run off (platform owners abscond with investor funds). More importantly, failing platforms were much less likely to run off in advance of major political events, but more likely to declare bankruptcy or run off after such events. These effects are more pronounced for politically connected platforms, platforms operating in provinces where local officials have close ties with central government, and in provinces with better local financial conditions. Our study highlights the role of political incentives on government regulatory intervention in platform failures.     

Diversification as a Public Good: Community Effects in Portfolio Choice

Within a rational general equilibrium model in which agents care only about personal consumption, we consider a setting in which, due to borrowing constraints, individuals endowed with local resources underparticipate in financial markets. As a result, investors compete for local resources through their portfolio choices. Even with complete financial markets and no aggregate risk, agents may herd into risky portfolios. This yields a Pareto‐dominated outcome as agents introduce “community” risk unrelated to fundamentals. Moreover, if some agents are behaviorally biased, or cannot completely diversify their holdings, rational agents may choose more extreme portfolios and amplify the effect.     

Monopolistic screening under learning by doing

This article investigates the design of incentives in a dynamic adverse selection framework where agents' production technologies display learning effects and agents' learning rates are private knowledge. In a simple two‐period model with full commitment available to the principal, we show that whether learning effects are over‐ or underexploited crucially depends on whether more efficient agents also learn faster (so costs diverge through learning effects) or whether it is the less efficient agents who learn faster (so costs converge). We further show that an overexploitation of learning effects can occur also if the full‐commitment assumption is relaxed.     

International tax arbitrage,currency options and put-call parity conditions

Using a finite-horizon general equilibrium model with uncertainty and money, we characterize situations where tax arbitrage opportunities may arise for international portfolio investors in an economy with heterogeneous capital income taxation where foreign currency exposure can be hedged using forward contracts and a set of currency options. We obtain tax-modified option prices similar to the no-tax ones, but augmented by tax-induced “risk-premium” terms; tax-modified put-call parity conditions are derived that revert to their standard (no-tax) format if the respective marginal agents in the bond and option markets are in identical tax brackets.     

基于内容提供商视角的传统媒体定价策略研究

随着移动互联网的发展,新媒体平台的出现和传统媒体的经营模式转型正在改变媒体市场结构。考虑传统媒体转型和新媒体内容外包,引入新媒体平台建立三方双边市场结构模型,考察竞争型市场结构中传统媒体平台的定价策略。研究发现：针对消费者和广告商进行差异性定价可以给传统媒体平台带来最佳收益,因此对消费者的低收费和补贴是合理的,并不构成非正当竞争;平台间差异化程度直接影响到其议价能力和利润水平;此外,消费者对广告的容忍程度也会影响媒体平台对广告商的定价,容忍程度越低,广告费用越高。     

区块链在我国资本市场领域核心场景应用研究

在分析区块链金融行业应用价值及境外经验的基础上,本文立足我国资本市场发展实际,以问题和需求为导向,思考利用区块链规划构建我国资本市场的核心场景应用,包括面向泛金融资产交易的新型基础设施,及以之为基础的统一债券交易平台、交易所场外交易平台、“云链一体化”新型证券信息服务平台、证券监管数据共享平台等。本文建议:一是由金融监管部门统筹建设国家级区块链泛金融新型交易基础设施;二是鼓励可行性较高的区块链应用场景以概念验证项目先行先试;三是加强区块链金融科技投入和相关人才培养;四是重视区块链交流合作和区块链知识产权。     

Two‐sided markets: a progress report

We provide a roadmap to the burgeoning literature on two‐sided markets and present new results. We identify two‐sided markets with markets in which the structure, and not only the level of prices charged by platforms, matters. The failure of the Coase theorem is necessary but not sufficient for two‐sidedness. We build a model integrating usage and membership externalities that unifies two hitherto disparate strands of the literature emphasizing either form of externality, and obtain new results on the mix of membership and usage charges when price setting or bargaining determine payments between end‐users.     

Overcoming Opportunism in Public‐Private Project Finance

The possibility of opportunistic behavior, whether by the private investors who operate public‐private projects or by the government agencies who oversee and administer them, can become a powerful deterrent to raising public‐private project financing, especially considering the scale of the investment in infrastructure. Nevertheless, both parties can protect themselves against the counterparty's possible opportunism by giving the investor an “exit” (or put) option and the public agent a “bail‐out” (or call) option on the private investor's shares. In describing the role and design of such puts and calls, this paper presents a mechanism for converting “natural monopolies” into competitive or contestable markets by using over‐the‐counter option contracts that combine the stability of long‐term contracts and the flexibility of short‐term contracts. In the language of economists, the exit/bail‐out option mechanisms presented here are seen as reducing barriers to entry by streamlining incomplete long‐term contracts and avoiding contractual problems related to “bounded rationality” and opportunism.     

Incentive-compatible advertising on nonretail platforms

Nonretail platforms enable users to engage in noncommercial activities, while generating user information that helps ad targeting. We present a model in which the platform chooses a personalized ad-display rule and an advertising fee (which depends on the targeted user group). The policy that maximizes the platform's advertising revenues creates an incentive for advertisers to strategize targeting. We provide a condition for incentive-compatibility of the first-best policy, and highlight the forces that make it harder to satisfy. We apply our result to examples of platforms. Our analysis of social networks turns out to be related to the “community-detection” problem.     

Limiting the ACA's Threats to Small Group Health Insurance Markets

We identify three threats to small group health insurance markets that may result from the 2014 implementation of certain provisions in the Affordable Care Act (ACA). First, small employers with predominantly low‐income employees may tend to opt out of small group markets because their employees will be better off with subsidized individual coverage. Second, small employers with employees of heterogeneous income levels will have strong incentives to offer coverage that is either “unaffordable” or fails to provide “minimum value” in order to preserve the availability of government subsidies for their low‐income employees. Finally, small employers that continue to offer group plans will face increased incentives to self‐insure those plans, further contracting small group markets and subjecting them to adverse selection. Collectively, these forces may destabilize small group markets and increase the ACA's fiscal cost. We therefore conclude by offering various reforms aimed at offsetting these risks and preserving the viability of small group markets.     

Asset Fire Sales and Purchases and the International Transmission of Funding Shocks

We identify a new channel for the transmission of shocks across international markets. Investor flows to funds domiciled in developed markets force significant changes in these funds' emerging market portfolio allocations. These forced trades or “fire sales” affect emerging market equity prices, correlations, and betas, and are related to but distinct from effects arising purely from fund holdings or from overlapping ownership of emerging markets in fund portfolios. A simple model and calibration exercise highlight the importance to these findings of “push” effects from funds' domicile countries and “co‐ownership spillover” between markets with overlapping fund ownership.     

Characteristics and mechanisms of not-fully marketized interest rates: Evidence from Chinese online lending

Most of the online lending rate are predominately determined by the platform, especially in the Chinese online lending markets, which indicates that the online lending rate is “not-fully marketized”. Based on a sample of 20 representative online lending platforms with daily data during June 1, 2017 to May 31, 2018 collected from Net credit eye and Lingyicaijing, our results, first, show that the average duration of loans, pending balance, newly added investors, and relative repayment amount are all significant factors for online lending rates. Second, from the view of the whole industry, the increase of the new investors also attracts more risk-seeking investors enter into the industry, who have considerable influences on online lending rates. Finally, when considering the credit rating of each individual platform, the explanatory power of the above factors is gradually weakened as the platform rating declines. This interesting finding suggests that the online lending rate of any platform can reasonably reflect its risks if the platforms keep better regulatory compliance. Our results provide theoretical and empirical supports for both regulators and investors.     

社交媒体上“用嘴投票”对管理层自愿性业绩预告的影响

本文研究了投资者 “股吧”讨论这种“用嘴投票”机制能否发挥治理作用进而促进管理层进行自愿性业绩预告。用上市公司股吧中的发帖量、阅读量和评论量来衡量投资者“用嘴投票”的参与程度,研究发现投资者“用嘴投票”参与度越高,管理层进行盈余预测自愿性披露的概率越大,且更愿意及时披露业绩下滑等坏消息。进一步研究发现,投资者“用嘴投票”是通过对股价产生影响、引发监管层关注和招致媒体报道这三个渠道对管理层产生预警进而发挥治理作用。且这一治理机制在管理层受到互联网信息影响可能性越大、公司中小股东户数越多以及论坛的讨论内容越负面时更为显著。     

Optimal auction design in two‐sided markets

A key feature of online markets for advertising (e.g., sponsored links) is that clicking rates depend on the searchers' expectations that the platform selects relevant advertisers. This article studies auction design by a platform that maximizes profits in the long run, where clicking rates are mechanism dependent. In line with the practice of the major search engines, the revenue‐maximizing mechanism is a scoring auction that combines the willingness to pay and the relevance to searchers of advertisers. By trading off rent extraction and clicking volume, this mechanism works as a cross‐subsidization device between searchers and advertisers.     

Macroeconomic Implications of “Deep Habits” in Banking

Recent empirical evidence shows that price‐cost margins in the market for bank credit are countercyclical in the U.S. economy and that this cyclical behavior can be explained in part from the fact that switching banks is costly for customers (i.e., from a borrower hold‐up effect). Our goal, in this paper, is to study the “financial accelerator” role of these countercyclical margins as a propagation mechanism of macroeconomic shocks. To do so, we apply the “deep habits” framework in Ravn, Schmitt‐Grohé, and Uribe (2006) to financial markets to model this hold‐up effect within a monopolistically competitive banking industry. We are able to reproduce the pattern of price‐cost margins observed in the data, and to show that the real effects of aggregate total factor productivity shocks are larger the stronger the friction implied by borrower hold‐up. Also, output, investment, and employment all become more volatile than in a standard model with constant margins in credit markets. An empirical contribution of our work is to provide structural estimates of the deep habits parameters for financial markets.     

Information and volatility links in the foreign exchange market

We apply the trading model of Fleming et al (1998 ). to a number of currency markets. The model posits that two markets can have common volatility structures as a result of receiving common information and from cross‐hedging activity where a position in one currency is used to hedge risk in a position taken in another. Our results imply that the model is effective in identifying common information flows and volatility spillovers in the currency markets and that some of these effects are lost when simply examining raw correlations. A series of specification tests of the 21 bivariate systems that are examined provides support for the trading model in the foreign exchange context.