It is a good time to reflect on Singles Day, a shopping carnival initiated by Alibaba that has just yielded a record-breaking sales of $17.8 billion, exceeding that on “Black Friday” in the US. It looks like everyone benefits: vendors sell, buyers get cheap goods and Alibaba profits through advertising fees and transaction commissions. But consider: to sell more, vendors lower product prices and sacrifice per-unit margins, yet they might not be able to make up on volume, as most of the items purchased are durable goods and therefore most of the increased sales on Singles Day are probably shifting sales from earlier or later periods.