Wei Li, speaking in the Institute for Advanced Study's High Energy Theory Seminar, presents work on the bulk mechanism behind the stringy exclusion principle in AdS3/CFT2 duality. The talk centers on string theory on AdS3 x S3 x M4 and its dual description as a symmetric product Sym^N(M4), focusing on what happens at finite N, where both the chiral-chiral spectrum and the number of polar terms in the elliptic genus become finite rather than infinite. Li shows how these finite-N boundary results can be reconstructed from the bulk side by summing contributions from a family of orbifolds of AdS3 x S3, each of which individually contributes an infinite series. The finite answer emerges only because of large cancellations driven by bosonic negative modes in the orbifold saddle points. The lecture assumes graduate-level familiarity with string theory and AdS/CFT, and runs through the calculation in detail for a specialist audience.