Hudbay Minerals Inc. stock is up about 30 per cent over the past three months. Despite the rally, the stock still sports a relatively cheap price-to-book ratio of about 0.6. We also continue to see insider buying. For example, on May 21, board chairman Stephen Lang bought 20,000 shares in the public market. However, most of the insider buying came from institutional players (not shown on chart). Over the past month, GMT Capital spent about $3.8-million buying stock, while Waterton Global Resource Management has spent about $2.9-million buying shares.