Recently, investors have started worrying a lot more that the stock market's rally has come too far too fast. With last week's poor employment report underlining the fact that growth in jobs hasn't kept pace with some other economic indicators, many investors have positioned themselves more defensively in anticipation of a potential downturn in stocks. Moreover, as earnings season begins, companies will reveal what really happened during the first quarter. This morning the stock market reflected that general uncertainty, and by 10:55 a.m. EDT the Dow Jones Industrials (DJINDICES:^DJI) were down 0.26%, with the broader markets down less sharply.

In their anxiety, investors have gravitated to more defensive stocks in an effort to protect themselves from losses. But this morning, health care stalwart Johnson & Johnson (NYSE:JNJ) is the biggest decliner in the Dow, falling 1.5% as the company got downgraded by an analyst at JPMorgan. The main problem the analyst cited was valuation, as J&J's stock has rocketed higher even as the company faces potential liability linked to recent product recalls. The drop emphasizes how important it is to look at valuation, as even defensive stocks can fall if their prices get too far out of line with their prospects.

UnitedHealth (NYSE:UNH) has also given up ground, down 0.8%. With little news on the company, the move appears just to be a small giveback of some of the massive gains that UnitedHealth and fellow health insurers enjoyed last week when looming Medicare reimbursement rate cuts suddenly turned into modest increases. It increasingly appears that Obamacare may prove more of a positive than a negative for UnitedHealth and its peers, even though the company will have to cover conditions it would previously have excluded.

Finally, Lufkin Industries (UNKNOWN:LUFK.DL) soared 38% on news that General Electric (NYSE:GE) will buy the oil field equipment company for $88.50 per share, or $3.1 billion. The move is obviously great news for Lufkin shareholders, but it also shows the extent to which GE is trying to move forward in building up its energy exposure. Given the huge ramp-up in domestic energy-production, GE's bid to become a vital piece of the energy infrastructure and equipment business is clearly a growth opportunity.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool recommends Johnson & Johnson and UnitedHealth Group. The Motley Fool owns shares of General Electric and Johnson & Johnson. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.