Unpleasantness greeted people who came back from the long holiday weekend, and it's a powerful reminder that while Wall Street action might seem sleepy, you just can't turn your back on the markets. Today came word of more

earnings warnings and downgrades, especially

Computer Associates

(CA) - Get Report

and

BMC Software

(BMCS)

, which combined to put the whammy on the

Nasdaq

at midday. The chip sector in general got downgraded, and

Abby Joseph Cohen

of

Goldman Sachs

was sounding downright pessimistic.

Key stocks:

Some

OPEC

members seem determined to

boost oil production, which sent stocks such as

Exxon Mobil

(XOM) - Get Report

,

Texaco

(TX) - Get Report

and

Chevron

(CHV)

down. Meanwhile,

Phillips Petroleum

(P)

was

upgraded.

What you might have missed:

The significance of insider trading is debated hotly among those involved in the markets, but we think that used wisely, it's vital information for average investors. Which is why we're beefing up our coverage in this area. Check out reporter

Robert Kowalski's

special on how the

Securities and Exchange Commission

is getting close to its first-ever written rules explicitly forbidding insider trading in certain circumstances. Meanwhile, the SEC also is pushing the nation's 20,000 investment advisory firms to

tell more about who they are and how they do business, so that the information can be communicated to investors on the Web.

What you don't want to miss:

Now that the news out of Japan seems to be turning bullish, be sure to check out our

Big Screen from the weekend, which focused on Japan funds. And what's the outlook in Mexico after the first new ruling party in 70 years was swept into power? Tune in tonight for

Ilana Polyak's

report.

Today's link:

Ever

wonder how...

Jonathan Krim is executive editor of TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, though he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. He welcomes your feedback at

jkrim@thestreet.com.