1) Earnings season begins: Forget Alcoa, it's about Wells Fargo on Friday. The main story in earnings this week will be JPMorgan Chase and Wells Fargo on Friday, particularly Wells.
Remember, Wells Fargo is nearly one-third of the mortgage market in the U.S.; early reports are that the pace of loan growth has slowed quarter-over-quarter, partly because refinancings have slowed. There could be a quarter-on-quarter decline in mortgage revenues.
Besides Wells Fargo, banks with large exposure to mortgages include Fifth Third, U.S. Bancorp, Suntrust Banks, and PNC Financial Services. Those with little exposure to mortgages include KeyCorp, Comerica, Zions Bancorp, and First Horizon National.
Bottom line: Given the likely negative mortgage loan growth (and weak loan growth elsewhere), you'll hear a lot about banks trying to increase fee income ... that means cross-selling products.
This is one of the reasons banks have been underperformers recently; the KBW Bank Index is up 7.5 percent, underperforming the S&P 500's 8.9 percent gain.
2) Housing IPO this week: Speaking of housing: Taylor Morrison Home will attempt to float 23.8 million shares at a price talk of $20 to $22 a share (symbol "TMHC"). It sells in Phoenix, the San Francisco Bay Area, Sacramento, and southern California, as well as Denver, parts of Florida, and in Austin and Houston.
Home building IPOs are a rarity: Tri Pointe Homes (symbol "TPH") went public at the end of January, 13.7 million shares at $17 a share, opened at $19.56, and at $19.39 today. That, as I recall, was the first home builder to go public in nearly 10 years.
3) Limit up, limit down is finally here. Today all stock exchanges will begin a rollout of a new series of "circuit breakers" designed to calm markets during high volatility. Stocks will be permitted to trade in bands that will allow them to (hopefully) stay open for trading more often.
The good news: This will make it less likely that stocks will be halted and will reduce the number of erroneous trades. The bad news: It will not apply in the first 15 minutes of trading or in the last half hour, leaving the entire market with no circuit breakers during that period. See my recent Trader Talk note.
—By CNBC's Bob Pisani