This paper studies modelling and existence issues for market models of option prices in a continuous-time framework with one stock, one bond and a family of European call options for one fixed maturity and all strikes. After arguing that (classical) implied volatilities are ill-suited for...

This paper studies modelling and existence issues for market models of stochastic implied volatility in a continuous-time framework with one stock, one bank account and a family of European options for all maturities with a fixed payoff function h. We first characterize absence of arbitrage in...

Empirically, we show that the proportion of stocks exhibiting conditional heteroscedastic residuals, is high. We suggested to use the market model with GARCH(1,1) residuals in order to describe daily stock returns and derived a test statistics for the null hypothesis of no abnormal returns,...

In this paper, we open up the black box that has been the introduction of open practices into firms’ commercial R&D strategies. Most of the existing research on the phenomenon of open innovation focuses on its interorganizational aspects. In contrast, the effect that the opening of boundaries...

In this paper, I describe and analyze the phenomenon of informal development collaborationbetween firms in the field of embedded Linux, a type of open source software. Toexplain the observed phenomenon of voluntary revealing, I develop a duopoly model ofquality competition. The central...

The link between firms engaging in open source software (OSS) development and the OSScommunity is established by individual developers. This linkage might entail a principalagentissue due to the developer’s double allegiance to firm and OSS community, and exposethe firm to the risk of losing...

This paper provides a quantitative study (N = 268) of patterns of free revealing offirm-developed innovations within embedded Linux, a type of open source software (OSS). Ifind that firms, without being obliged to do so, contribute many of their own developmentsback to public embedded Linux...

Network externalities spur the growth of networks and the adoption of network goods intwo ways. First, they make it attractive to join a network with a large installed base.Second, they make it attractive for network members to actively recruit new members.Despite indications that this “peer...