Take a look at the companies making headlines after the close: Robinhood, the retail brokerage’s shares, gained 4.5% after the company announced a $1 billion share buyback program. Robinhood management expects to implement the program within two to three years, starting in the third quarter of 2024, the press release said. Cava Group – Shares fell 5% in after-hours trading even though the restaurant chain reported first-quarter earnings and revenue that were well above expectations. Cava reported earnings of 12 cents per share on revenue of $259 million, while analysts polled by LSEG expected earnings of 4 cents per share on revenue of $246 million. Earlier Tuesday, Cava shares hit a 52-week high . Box — Shares of the cloud storage company rose 1.2% on better-than-expected earnings and revenue. Box reported adjusted earnings of 39 cents per share, while analysts polled by LSEG expected earnings of 36 cents per share. Revenue was $264.7 million, beating expectations of $262 million for the quarter. Microchip Technology — Microchip shares fell 2.8% after the company said it intends to raise $1.1 billion of convertible senior notes due 2030 in a private placement, subject to market conditions and other factors. American Airlines – shares of the air carrier fell by more than 6%. American Airlines lowered its sales forecast for the second quarter. The company also expects adjusted earnings of $1 to $1.15 per share for the period, compared with a previous forecast of $1.15 to $1.45 per share, according to a regulatory filing. The updated adjusted earnings forecast also fell below FactSet consensus expectations of $1.30 per share. United Airlines — Shares fell 2% after the airline released an update on its financial outlook. United reiterated its second-quarter earnings forecast of $3.75 and $4.25 per share, according to a regulatory filing. — CNBC’s Darla Mercado contributed reporting.