CNBC.com's MacKenzie Sigalos brings you the day's top business news headlines. On today's show, CNBC's Eamon Javers walks through the suspected Russian cyber attack that breached the networks of federal agencies and major corporations. Plus, CNBC.com's Lauren Feiner breaks down the flurry of antitrust litigation facing Google.

Suspected Russian hack is much worse than first feared: Here's what you need to know

The scale of a sophisticated cyberattack on the U.S. government that was unearthed this week is much bigger than first anticipated.

The Cybersecurity and Infrastructure Security Agency said in a summary Thursday that the threat "poses a grave risk to the federal government."

It added that "state, local, tribal, and territorial governments as well as critical infrastructure entities and other private sector organizations" are also at risk.

CISA believes the attack began at least as early as March. Since then, multiple government agencies have reportedly been targeted by the hackers, with confirmation from the Energy and Commerce departments so far.

Google's antitrust mess: Here are all the major cases it's facing in the U.S. and Europe

Google now faces several antitrust challenges around the world, including three government lawsuits filed in the U.S. in the last two months alone.

Government agencies have been scrutinizing the company for years, though, with the European Commission cracking down on the search giant well before U.S. regulators caught up. The Commission has already levied billions of dollars in fines against Google in three separate competition cases, which Google has appealed.

Traders brace for wild action and historic volume ahead of Tesla's entry into the S&P 500

Electric vehicle maker Tesla is poised to enter the S&P 500 in what will be the largest rebalancing in the history of that index.

The new index with Tesla in it begins trading on Monday, but all the trading action happens at the close on Friday.

The trading volume will be so heavy, some are concerned it could result in fireworks at the close.

S&P estimates that approximately 129.9 million shares of Tesla will need to be purchased to add to the S&P 500. At the current market price of $655, indexers would need to buy $85.2 billion in Tesla stock at the close on Friday. However, there are billions more that will need to be bought by "closet indexers" that do not officially pay S&P, but nonetheless track the index. No one knows how much these "closet indexers" will buy, but it could be 50%-100% above the "official" $85.2 billion estimate.