As the new year starts, investors are probably wondering what the best FTSE 100 stock to invest in is.
Last year, it was the mining company, Fresnillo, that was the darling of the index, after its 394.8% rise.
I turned to ChatGPT to see what it thought was the best company to invest in the Footsie for 2026. Surprisingly, it mentioned a stock I hadn’t even considered.
The stock in question is AstraZeneca (LSE:AZN). Let’s see below why I’m not so sure about the generative AI’s suggestion.
I’m not so sure…
While I think that AstraZeneca is a great company, it’s the reasons provided by ChatGPT that I’m not so sure about.
The first reason mentioned is the pharmaceutical giant’s strong share price performance of about 30% in 2025. The problem with this is that it is a very basic analysis and ignores the principle that just because a company has performed well in the past, it doesn’t mean it will in the future.
Furthermore, some of the other key reasons it mentioned don’t make sense to me. For example, it said the company has a valuation appeal. With a price-to-earnings (P/E) ratio of 30.9, I don’t believe its shares are valued cheaply at all. I think ChatGPT has it wrong here.
That said, there are things to like about the company. Notably, it has a strong pipeline of new pharmaceutical drugs that could drive up revenue and earnings if regulatory approval is granted.
However, because of valuation concerns and some other factors, such as the company having $24bn of net debt on its balance sheet, I don’t think it will turn out to be the best FTSE 100 stock for 2026.
A dirt-cheap alternative
My pick for 2026 is another mining stock, like Fresnillo. I think Rio Tinto (LSE:RIO) could be a great stock for investors to consider in the coming year.
With a P/E of only 13.1, it’s far cheaper than AstraZeneca. But what appeals to me the most is that it’s not priced like an AI stock, while being a potential big winner as the AI market continues growing.
How did I make this link with AI, you may be wondering right now?
Well, huge sums of money are anticipated to be spent on AI infrastructure over the next few years. For example, $3trn is expected to be spent on AI data centres through to 2029.
This presents a great opportunity for Rio Tinto, which is a key miner and producer of two of the key metals needed to make this happen: aluminium and copper.
Its Oyu Tolgoi mine in Mongolia hosts one of the world’s largest known copper deposits. This puts the miner in a strong competitive position.
There are risks with holding shares in the metal miner. For example, commodity price fluctuations could have a big impact on the company’s earnings, which could hurt its shares if there are adverse movements in metal prices.
Overall, though, I still think Rio Tinto shares are among the most compelling in the FTSE 100 over the coming year. Therefore, I think investors should consider its shares.
