Duolingo shares rallied on Monday after two Wall Street firms issued bullish research on the language-learning platform. Citigroup initiated coverage with a Buy rating and a $400 price target, while KeyBanc Capital Markets upgraded the stock to Overweight from Sector Weight and set the Street-high target of $460. Both brokerages argued that investor concerns about artificial-intelligence risks have been overstated. The analysts pointed to Duolingo’s planned product rollouts, pricing levers and international expansion as catalysts that could accelerate user growth and monetisation over the next several years. The twin endorsements sent Duolingo stock up as much as 10% intraday to about $327, extending a rebound that began earlier this month. The shares pared some gains in afternoon trading but remained well above last week’s close.