You’re shopping and see a great deal so you Tweet it out to your friends. Or after you bought something new online your purchase is then “shared” on Facebook. When you post something you purchased, is that really just a social media post or is it an advertisement? The only thing that separates it from a traditional advertisement is that nobody paid you to advertise for them. It’s becoming more common for consumers to share this “pro bono” form of advertising but what happens to consumers when they see things that you’ve posted? Two of my independent study students and I just studied this and found that online retailers get a boost when purchases are posted online. The paper was presented a few months ago at the Big Data Analytics Conference at NYU Stern. A copy of the presentation can be found here.