Living with Mom and trading on margin. The regular investor gets in on Wall Street's record stock borrowing binge

HOUSTON — During a late night at home in May 2021, Hy Luu, a 29-year-old engineering consultant, was researching how to obtain more capital to invest in shares of Tesla . That's when he discovered margin investing: the act of borrowing money from a broker to buy securities such as stocks, while using existing investments as collateral. Borrowing would give him more buying power, and he could pay it back as the stock appreciated. The main risk would be a margin call, or having to deposit more money into the account, if its value fell.