The earnings season rolls on with nearly a fifth of the companies in the S&P 500 (^GSPC -1.46%) reporting results this week, according to data provider FactSet. Walt Disney Co (DIS -2.68%) is the lone component of the Dow Jones Industrial Average (^DJI -1.24%) to do so this week (Tuesday). 

One of the most heavily anticipated earnings reports will be that of Tesla Motors Inc (TSLA -2.03%) on Wednesday afternoon (if Tesla is part of your portfolio or on your watchlist, make sure you track these two under-the-radar metrics in the report.) 

Bloomberg reports today that the stocks of the 65 companies in the NASDAQ 100 index that have reported earnings in the past three weeks moved up or down by an average of 5.1% in the trading session that followed immediately after the report (the average gain was 4.8%, while the average loss was 5.3%), the highest average since 2012. 

With shares of Tesla trading at 85 times next year's earnings-per-share estimate and having gained 20% year to date (as of Friday's close), there's every reason the market could greet Wednesday's report with substantial volatility, too. 

The Greek market is back online 
The Athens Stock Exchange resumed activity this morning following a five-week suspension in trading. On the open, the Athex Composite Share Price index plummeted nearly 23% within the first five minutes of trading before recovering somewhat and closing with a loss of "only" 16.2%. 

Interestingly, the Global X FTSE 20 Greece ETF (GREK -3.68%), which tracks the top 20 companies listed on the Athens Exchange and continued to trade throughout the suspension, is up less than one percent at 1 p.m. EDT. That suggests the ETF did an first-class job with regard to price discovery. While the Athens Exchange was shuttered, average daily volume in the ETF more than doubled relative to the prior three months. 

For reference, in its 119-year history, the Dow Jones Industrial Average has recorded just four instances of daily declines greater than 10%, only one of which exceeded today's loss on the Athens Exchange (Black Monday, Oct. 19, 1987, when the Dow fell 22.6%.) 

All eyes on Friday's jobs report 
This week's most significant economic data release is the Labor Department's employment situation report for July, which drops on Friday at 8:30 a.m. EDT. In last week's statement from the Federal Open Market Committee, Federal Reserve policymakers said they would need to see "some further improvement in the labor market" before implementing the first interest rate hike. It remains overwhelmingly likely, but as Ms. Yellen has repeatedly emphasized, it all comes down to the economic data. 

Fed chair Janet Yellen and her colleagues will be scrutinizing Friday's report closely, including the participation rate and average hourly earnings, to try to divine the amount of slack in the labor force. Economists' consensus estimates have the economy adding 224,000 last month and the unemployment rate unchanged at 5.3%.