Image source: Getty ImagesFor those who invested in Nvidia stock back in the day and held on, the returns have been staggering. Between March 2018 and late 2025, its investment in Nvidia went up 3,155%! Given Baillie Gifford’s track record of unearthing top growth stocks like Nvidia and Tesla, it’s worth keeping an eye on what new shares it has been buying. BillionToOneMy initial takeawayStepping back, I see a few things here that indicate BillionToOne could become a top growth stock. It’s also working on tests that detect cancer early, which could become the most exciting market of all.