Here are four things you need to know before the opening bell rings in New York:

1. Stocks gunning for new all-time highs: Monday's negation of Friday's massive selloff, and on decent volume, is a very bullish sign. So was the report out of Morgan Stanley (MS) that trading volumes are up across the board.  Bullish traders trade more.  Currently U.S. stock futures are up another 50 basis points while European markets are all rising in early trade.  Most Asian markets closed the day with big gains, from 2% - 4%.  

Here are the key numbers to watch:

• 2120 has held the S&P captive since late February.  The S&P is slated to open just about 18 points shy of that mark.
• 18290 is the same mark for the Dow Jones Industrials.  They will need about 250 points to crack that level.
• 5042 was tagged in mid-March by the Nasdaq.  It should open around 5020, giving it the best shot at hitting new highs today.

CNNMoney's Fear & Greed Index shows that investors are feeling increasingly greedy.  While this is a bearish sign for contrarians, it shouldn't bother the markets today which will be running on momentum.

2. The thick spot of earnings season: We're in the middle of earnings season and today marks the heaviest day in the cycle thus far on a market cap basis.  Big companies reporting today include:

IBM (IBM) reported last night.  United Technologies (UTX), SAP (SAP), Dupont (DD), Travelers Insurance (TRV), Harley-Davidson (HOG), Lockheed Martin (LMT), Under Armour (UA), Verizon (VZ, Tech30) and Kimberly-Clark (KMB) report ahead of the open.

Amgen (AMGN), Chipotle (CMG), Yahoo (YHOO, Tech30), Ace Ltd. (ACE), Broadcom (BRCM), and YUM Brands (YUM) all report after the close.

3. Greece revisited: Just when we thought we could forget about Greece for a while, the debt-plagued nation pops up in the news again.  On Monday, the Greek government asked all public sector organizations to hand over their cash reserves, just in case it needs to borrow the money. Clearly with this extreme move the government is signalling that it is running short of money to service its debts and pay wages and pensions.

This is having an impact on the euro trade, notes Angus Campbell, senior analyst at FxPro. "Reports that Greece is preparing to default on its up and coming IMF loan repayments in May and June," states Campbell, "unless a deal is struck by the end of this month have done little to attract buyers of the euro and we’re unlikely to see any upside for some time given that QE has only just got underway."

If Greece defaults, the country may have to abandon the euro and start printing its own money. The euro was 0.7% weaker against the dollar on this news.