Researchers at the University of Iowa used financial models to track the progression of HIV strains. Professor Hillel Haim, the study's author discussed some of the challenges of creating an HIV vaccine. Professor Hillel Haim The 'moving target' is an HIV protein researchers have been collecting and analyzing in patient blood samples since the 80s. The team found that the protein shares the same 'volatility' as stock prices, meaning they both fluctuate and are unpredictable. Researchers can use this financial model to predict changes in HIV and match potential vaccines to certain strains.