Abhi Pingle is a savvy trader. For a year and a half, he worked at Optiver, one of the top high-frequency trading firms. HFT shops employ traders known as quants who are highly skilled in programming and quantitative analysis. Mom-and-pop investors can’t hope to compete with quants’ trading know-how, but Pingle wants to change this. He and his two cofounders, brother Arijit Pingle and TK Kwon, have raised $20 million across two funding rounds to launch Theo, a trading platform that lets users earn money from strategies usually reserved for top-tier HFT firms.