When I scout for new additions to my UK shares portfolio, I gravitate towards market trends. Currently, commodities are in the spotlight. While some, like gold and silver, have already surged, there’s still significant potential in other base metals such as iron ore and copper. One way to tap into a move in a commodity is by searching for mining companies. Rio Tinto (LSE: RIO) operates in 35 countries and has a portfolio consisting of iron ore, copper and aluminium. It trades at 4.5 times forward EBITDA, compared with a sector average of 5.5 times. There has been a lot of change happening at Rio Tinto. Rio Tinto’s copper assets, which are worth $21bn, are now bigger than its iron ore business. This reflects the company’s investment in a massive copper mine in Mongolia, which is just starting production. Copper is more exciting than iron ore because it is crucial to the energy transition, and its demand is expected to double by 2040. However, there might be some supply shocks along the way, which could push up its price. Rio Tinto’s increasing exposure to copper might make its equity story more attractive to investors. A slight arbitrage benefit for investing...