Written by: Jeremie Capron Bill Alpert, Barron’s Senior Editor, stirred the pot a bit last week when he published Robo-Boosted Drone Maker AeroVironment May Be Headed for a Fall . In his article, he states that “the only apparent explanation” for military drone maker AeroVironment’s skyrocketing stock price is the fact that “trendy ETFs like ROBO Global Robotics & Automation (ROBO)” have made AeroVironment (AVAV) a top holding. It’s an interesting presumption, but it’s a skewed concept that does AeroVironment—and ROBO Global for that matter—a considerable disservice.What Alpert (or perhaps hedge fund manager Ben Axler who is quoted as the source for the theory) must not have realized is that this explanation holds no water. AeroVironment is a bellwether member of the ROBO Global Robotics & Automation Index , which means it represents less than 2% of the index and of the ROBO ETF. At that small percentage, even the large inflows into the flagship Robotics & Automation ETF could not be the main reason for the stock’s impressive advance this year. We estimate that the ROBO ETF accumulated just over 600,000 shares of AVAV in the first nine months of 2017, which represents an average of 3,200 shares per day, compared to the daily average 227,000 shares that traded on the market over that period. It would it be quite improbable—if not wholly impossible—for a buyer that is less than 2% of the flow in a stock to move its price materially. In fact, most institutional traders would agree that it would take more than 10 times that level of trading to have a significant market impact.Yet according to Alpert and Axler, this isn’t the first time ROBO Global’s buying practices have influenced the valuation of a stock in this way. The article states that it’s “a story Axler believes he’s seen before” when shares of iRobot were “catapulted by the buying of the same ETF.”While I have the utmost respect for Bill Alpert and Ben Axler, I do wish they had taken a closer look at the methodology behind the ROBO Global Index before coming to their conclusions. Had they done so, they would have seen that, in contrast to certain other ETFs that concentrate their holdings on just a few dozen of the largest market-cap weighted robotics and automation companies, the ROBO Global Robotics & Automation Index includes over 80 companies around the world. Members of the Index are either “bellweather” companies (established leading players whose core business is directly related to robotics, automation and artificial intelligence, or “RAAI”) and “non-bellweather” companies (companies who have a defined portion of their business and revenue in RAAI and have the potential to grow through innovation and marketplace adoption).Once companies are selected by our team of industry experts based on their revenue exposure to RAAI technologies and market leadership, we use a modified equal-weighted approach designed to provide diversified exposure to the growth and return potential of RAAI. Notably, the Index rebalances quarterly, thereby naturally selling high and buying low on a regular basis. This reduces company-specific risk by limiting the weighting of every one of its holdings. Including the largest, the most popular, or even the most promising companies in the space. And yes, including both AeroVironment and iRobot. In addition, the methodology caps maximum ownership across funds that track the ROBO index at a combined 5% of free floating shares for every index member. Related: Investing in Robotics? Follow These 5 Simple Rules