Twitter timelines are increasingly populated with brand tweets that are linked to public events, a practice that is also known as real-time marketing (RTM). In two studies, we examine whether RTM is an effective strategy to boost sharing behavior, and if so, what event- and content-related characteristics are likely to contribute to its effectiveness. A content analysis of brand tweets from Nielsen’s top-100 advertisers (n=1500) shows that not all events are equally effective. RTM is only a more effective strategy (vs. no real-time marketing), when brand messages are linked with unpredictable events but not when brand messages are linked with predictable events. In a follow-up study, we examined what content characteristics improve the shareability of predictable RTM messages. A content analysis of RTM messages (n=143) from the Forbes top-100 brands showed that predictable events yield more retweets when the event is visually integrated in the brand tweet (vs. not visually integrated). The presence of event-driven hashtags did not lead to more retweets. Implications for theory and practice are discussed.