As an AI language model, I can provide information on some notable business-related legal cases decided in 2021. However, determining the “top” cases can be subjective, as it depends on various factors like significance, media coverage, and jurisdiction. Here are ten cases that received attention during the year:

1. Apple Inc. v. Epic Games, Inc.: The case focused on Apple’s App Store policies and alleged antitrust issues.
2. Facebook, Inc. v. Federal Trade Commission & State Attorneys General: The FTC and multiple state attorneys general sued Facebook alleging antitrust violations.
3. Google LLC v. Oracle America, Inc.: A long-standing copyright and fair use case related to the use of Java APIs in Android mobile devices.
4. Johnson & Johnson Talcum Powder Litigation: Several lawsuits alleged that talcum powder products caused cancer, resulting in substantial damages awarded.
5. Mitsubishi UFJ Trust & Banking Corp. v. Petrobras America Inc.: A complex case involving a bondholder dispute between Petrobras and its investors.
6. Nikola Corporation Securities Litigation: Investors filed lawsuits against electric vehicle start-up Nikola Corporation for alleged fraud and misleading statements.
7. Purdue Pharma L.P. Bankruptcy: Purdue Pharma filed for bankruptcy as part of a settlement related to the opioid epidemic, facing numerous lawsuits.
8. Securities and Exchange Commission v. Ripple Labs Inc.: The SEC filed a lawsuit against Ripple Labs, alleging the unregistered sale of securities (XRP).
9. Tesla, Inc. v. Martin Tripp: Tesla sued a former employee for trade secret theft and leaked confidential information.
10. Volkswagen Diesel Emissions Scandal (various cases): Legal actions and settlements continued regarding Volkswagen’s emissions scandal, affecting multiple jurisdictions.

Please note that this list is not exhaustive, and the importance of cases may vary based on individual perspectives and interests.