I looked into this idea of turnover relative to market cap since...

I looked into this idea of turnover relative to market cap since you mentioned BHP, and over the past year, it probably doesn't surprise you to learn that some of the stocks with the highest level of short interest also tended to have consistently high turnover relative to market cap. Some of the stocks that were notable for consistently high liquidity were things like Blue Sky Alternatives (which bombed out), but also Afterpay (which has skyrocketed) and Bellamy's, which sort of looks like a hockey stick. In relation to similar industry, Mineral Resources, Kidman, Lynas, Syrah and AVZ all have similar liquidity to market cap but have had quite different paths for their prices, so there's not really a big pattern in relating high turnover to the general direction over the past year. Pilbara has considerably less turnover per market cap, though it still fell substantially over the year. This makes me think that the high turnover in of itself is not an indicator of manipulation, though it doesn't rule it out.