The most-talked-about stocks in the Reddit subforum Wallstreetbets were advancing hours before Tuesday's opening bell.

Avis Budget Group (CAR) jumped nearly 11% pre-bell, following a 23% increase at Monday's close.

UnitedHealth (UNH) was 6.4% higher premarket, reversing a 0.4% decline from the previous session. The company reported higher Q1 adjusted earnings and revenue, and raised its full-year adjusted EPS outlook.

AST SpaceMobile (ASTS) advanced by 3.8% in premarket activity, swinging from a 5.3% fall from Monday.

Amazon.com (AMZN) was up 2.7% in pre-bell hours, reversing a 0.9% decline from the previous session.

Strategy (MSTR) was 1.9% higher pre-market, after a 2.6% increase at Monday's close.

Rocket Lab (RKLB) rose by 1.8% premarket, following a 5.5% gain in the previous session.

Tesla (TSLA) was 0.6% higher pre-bell.

Microsoft (MSFT) was up 0.4% hours before market open, following a 1.1% decline at Monday's close.