Prior literature suggests that multimarket contact can mitigate product-market rivalry between firms due to retaliation threats but that it may intensify factor-market rivalry due to imitation threats. We propose that, in platform markets, multimarket contact also makes salient network-preemption threats—that is, threats of rival firms developing network effects to capture and hold substantial market share. Since network-preemption threats are more pronounced (1) for within-platform rivals (than between-platform rivals), (2) at the early stage of the platform market's evolution (compared with the mature stage), and (3) for competitors facing installed-base disadvantages, we predict that these three factors will positively moderate the effect of multimarket contact on the likelihood of competitive action. Analysis of patent litigation between smartphone manufacturers during 2008–2021 largely supports our theoretical framework.
