This paper is to provide a theoretical investigation on real-money trading (RMT) ob-
served frequently in online games. To overcome former studies focused much on descrip-
tion itself, economic incentives behind RMT are modeled and identi?ed by reconsidering
economic studies related. Firstly, RMT is analyzed by its modes of trading. It is shown
that two modes of trading, the continuous and the discrete, have di?erent consequences
on the con?guration of RMT market. Secondly, economic impacts of RMT are explored
in the context of network externalities. Thirdly, welfare implications between servicing
?rm and players are adressed in the dynamic context. Finally, two issues of RMT, gold
farming and micro-payment, are shortly addressed as an application for the analysis.