By James Dennin for Kapitall. The London Metals Exchange (LME) oversees more than 700 warehouses to make sure the pipeline that takes metals from miners, to distributors, to manufacturers—stays clear. The wait-time on aluminum has grown from 15 months to almost two years over the last 12 months, prompting some lawmakers to call for reforms. The LME issued a ruling that would require storage facilities with the longest waits to release more metal than they receive. That new rule would lower wait-times on the metal, helping keep prices low. Aluminum prices in particular have been rising as car manufacturers switch away from heavier metals like steel. Growing prices have beer manufacturers in particular concerned. Some estimates tally the additional cost of scarce aluminum to these companies at $6 billion. Reforms at the LME would certainly help the situation, although they would take time to have a measurable effect. With that in mind, we decided to screen metals stocks for promising names. To do that we looked for stocks in basic materials: industrial metals, silver, copper, gold, and aluminum. We then ran a screen on those stocks for companies with spikes in institutional purchasing from groups like hedge funds. Since the managers of these funds are professional investors, they often have access to better information than retail investors. We found 6 metals companies that had spikes in purchasing. Do you think these firms are right to be bullish on metal? Use the list below to begin your analysis and let us know what you think in the comments. Click on the interactive chart to view data over time. 1. Alcoa, Inc. ( AA): Engages in the production and management of aluminum, fabricated aluminum, and alumina. Market cap at $19.48B, most recent closing price at $16.56. Net institutional purchases in the current quarter at 73.6M shares, which represents about 6.29% of the company's float of 1.17B shares.