The stock market is indeed open for a full trading session on New Year's Eve, Thursday, Dec. 31, 2020. But for what it's worth, bond traders do get a slightly shortened day; the bond markets will close up shop a little early, at 2 p.m. ET.
Why do bond markets close slightly early (at 2 p.m. ET) on December 31 whereas the stock market closes at the regular time?