fix: update the README.md

README.md

@@ -102,3 +102,14 @@ QA pairs are stratified by market regime (bull/bear/sideways/crisis) to enable p
 ### Point-in-Time (PiT) Constraint
 
 All questions use only information available at or before the `decision_date`. Ground-truth answers are computed from realized future data that is never included in the question or context.
+
+### Citation
+
+```bibtex
+@article{zhao2026portbench,
+  title={PortBench: A Correlation-Aware, Full-Pipeline Benchmark for LLM-Driven Portfolio Management},
+  author={Zhao, Yuxuan and Chen, Sijia and Su, Ningxin},
+  journal={arXiv preprint arXiv:2605.27887},
+  year={2026}
+}
+```