The most-talked-about stocks in the Reddit subforum Wallstreetbets were mixed before Wednesday's opening bell.

MP Materials (MP) advanced by 4.3% pre-bell, following a 20% rise in the previous session.

Opendoor Technologies (OPEN) rose by 3.9% premarket, after closing Tuesday with a roughly 16% gain.

UnitedHealth Group (UNH) was 0.3% higher pre-bell, swinging from a 3% decline at Tuesday's close.

ASML Holding (ASML) declined by 8.2% in pre-bell activity, reversing a 2% increase from Tuesday's session.

Advanced Micro Devices (AMD) fell by 1.1% hours before market open, following a 6.4% rise in the previous session.

Nvidia (NVDA) was down 0.6% in premarket hours, swinging from a 4% increase at Tuesday's close.

Tesla (TSLA) was 0.4% lower pre-bell, after a 1.9% decline Tuesday.

Robinhood Markets (HOOD) was down by 0.4% premarket, following a 0.4% fall in the previous session.