The TLDR: A Dem-controlled government doesn't mean everything will be a piece of blue cake — especially with a 50/50 Senate where VP-elect Harris holds the tiebreak. But it does mean legislation will be easier to pass than it is now (with a Dem-controlled House and a GOP-controlled Senate). Soo...
Big Tech... could see bigger regulation efforts. Think: legislation targeting consumer-data privacy, halting Big Tech takeovers, and potential breakups of tech "monopolies," like Facebook, Amazon, and Google. Also: reform to Section 230, which protects social media companies from being liable for users' posts. A year ago, Biden even called for 230 to be repealed. Losing 230 immunity would be brutal for Facebook and Twitter — they could get sued every time someone shared something harmful or false (aka: often).
Big Banks... could get hit by hands-on, progressive regulation. Gary Gensler, Biden's expected pick to lead the SEC, will likely move to reign in Wall Street. And incoming Senate Banking Chairman Sherrod Brown wants government-administered bank accounts — and tight financial regulation. Meanwhile: Biden wants to raise the corporate tax rate to 28% from 21% (Trump cut it from 35% to 21%). America's 10 largest banks could see their combined yearly profits slashed by $7B+. And investment banking sales could fall for bigshots like JPMorgan Chase, Morgan Stanley, and Citi if capital gains taxes are raised for rich clients. One bright spot: Biden's stimulus could help banks avoid loan losses by helping borrowers.