Diamond Offshore Drilling (NYSE: DO) volatility slightly higher as DO at record high. DO, a drilling service provider to the energy industry, closed at $113.04. RIG and GSF, drilling service providers, announced a merger of equals on 7/23. DO August option implied volatility of 36 is above its 26-week average of 33 according to Track Data, suggesting slightly larger price risk.

Ensco International (NYSE: ESV) volatility elevated as ESV at record high. ESV, an offshore contract drilling company, closed at $65.90. RIG and GSF, drilling service providers, announced a merger of equals on 7/23. ESV has a market cap of $9.8 billion with long-term debt of $308 million. ESV had March 2007 quarterly net income of $232 million on total revenue of $514 million. LYON has a $59 price target on ESV. ESV August option implied volatility of 40 is above its 26-week average of 33 according to Track Data, indicating larger price fluctuations.

Atwood Oceanics (NYSE: ATW) August implied volatility elevated as ATW at record high. ATW is engaged in the business of international offshore drilling of exploratory and developmental oil and gas wells and related support management and consulting services. ATW closed at $74.36. ATW will report EPS on August 7th. RIG and GSF, drilling service providers, announced a merger of equals on 7/23. ATW August option implied volatility of 39 is above its 26-week average of 33 according to Track Data, suggesting larger risk.

Rowan (NYSE: RDC) August volatility elevated into EPS. RDC, a provider of international and domestic offshore contract drilling services, will announce EPS on August 2nd. Morgan Keegan says: "We are lowering our estimates on RDC as we build in lower day rate assumptions and a delayed recovery for US Gulf commodity jackups." RIG and GSF, drilling service providers, announced a merger of equals on 7/23. RDC August option implied volatility of 46 is above its 26-week average of 32 according to Track Data, suggesting larger risk.

Daily Update is provided by Stock Specialist Paul Foster of theflyonthewall.com.

MOST NOTEWORTHY: Shire Plc (SHPGY), Cablevision Systems Corp (CVC), Yahoo! (YHOO), Ensco International (ESV) and Clear Channel Outdoor Holdings (CCO) were today's noteworthy downgrades:

• JP Morgan downgraded shares of Shire Plc (NASDAQ: SHPGY) to Neutral from Overweight to reflect risk of Adderall XR patients switching to Vyvanse.

• Deutsche Bank cut Cablevision (NYSE: CVC) to Hold from Buy, saying shares reflect a likely higher bid from the Dolan family.

• ThinkEquity downgraded shares of Yahoo! (NASDAQ: YHOO) to Accumulate from Buy following checks that indicate marginal Panama upside, poor execution in premium display and an incomplete/vulnerable non-premium display strategy.

• Credit Suisse cut Ensco International (NYSE: ESV) to Underperform from Neutral on valuation.

• SMH Capital downgraded Clear Channel Outdoors (NYSE: CCO) to Sell from Neutral and recommended investors to swap into Lamar Advertising Co (NASDAQ: LAMR), based on the company's higher-quality name in the outdoor advertising sub-space...

OTHER DOWNGRADES:

• Baidu.com (NASDAQ: BIDU) was cut to Hold from Buy at Citigroup.

• Brinker International (NYSE: EAT) was downgraded to Underweight from Equal Weight at Morgan Stanley.

• Hilliard Lyons downgraded Nike Inc (NYSE: NKE) to Neutral from Long-Term Buy.

• Buckingham cut Ashland Inc (NYSE: ASH) and Cabot Corp (NYSE: CBT) to Neutral from Accumulate.

Analyst summaries provided by TheFlyOnTheWall.com (subscription required).

MOST NOTEWORTHY: Linear Technology Corp (LLTC), Anheuser-Busch (BUD), Best Buy (BBY), Bankrate (RATE) and Ensco International (ESV) were today's more noteworthy downgrades:

• Linear Technology Corp (NASDAQ: LLTC) was cut to Sell from Neutral at Merrill citing slowing revenue growth and valuation...

• AG Edwards downgraded Anheuser-Busch (NYSE: BUD) to Hold from Buy on valuation...

• Goldman said Best Buy's (NYSE: BBY) fundamentals remain at risk after the Q1 report and cut shares to Neutral from Buy...

• AG Edwards cut both Bankrate (NASDAQ: RATE) and Ensco International (NYSE: ESV) to Hold from Buy on valuation...

OTHER DOWNGRADES:

• Merck & Co (NYSE: MRK) was cut to Market Perform from Outperform at Raymond James.

• Schlumberger Ltd (NYSE: SLB) was downgraded to Neutral from Add at Calyon.

• ThinkEquity downgraded Color Kinetics (NASDAQ: CLRK) to Accumulate from Buy.

• Maxwell Technologies (NASDAQ: MXWL) was cut to Market Perform from Outperform at JMP Securities.

• Occidental Petroleum Corp (NYSE: OXY) was downgraded to Hold from Buy at Deutsche Bank.

Analyst summaries provided by TheFlyOnTheWall.com (subscription required).

MOST NOTEWORTHY: The more noteworthy downgrades today came from Calyon, which cut five companies in the oil services and equipment sector:

• Calyon is taking a more cautious stance due to valuations in the sector. The firm believes strong fundamentals are now reflected in share prices. As such, Calyon downgraded Global Industries, Ltd (NASDAQ: GLBL), Ensco International Inc (NYSE: ESV), Transocean Inc (NYSE: RIG) and Schlumberger Ltd (NYSE: SLB) to Add from Neutral and downgraded Gerber Scientific, Inc (NYSE: GRB) to Neutral from Add...

OTHER DOWNGRADES:

• Piper Jaffray cut ValueClick, Inc (NASDAQ: VCLK) to Market Perform from Outperform.

• UBS cut Lyondell Chemical Co (NYSE: LYO) and IndyMac Bancorp, Inc (NYSE: IMB) to Neutral from Buy.

• Goldman downgraded Worthington Industries, Inc (NYSE: WOR) to Sell from Neutral.

• Matrix USA cut Allergan, Inc (NYSE: AGN) to Sell from Hold and Fifth Third Bancorp (NASDAQ: FITB) was downgraded to Underperform from Market Perform at Keefe Bruyette.

Analyst summaries provided by TheFlyOnTheWall.com (subscription required).

MOST NOTEWORTHY: Wal-Mart (WMT) and Motorola (MOT) were the most notable downgrades this morning.

• Goldman Sachs downgraded Wal-Mart Stores Inc. (NYSE: WMT) to Neutral from Buy; citing weaker sales and expected heavy markdowns.

• Credit Suisse removed shares of Motorola Inc. (NYSE: MOT) from their Focus List.

OTHER DOWNGRADES:

• Bear Stearns downgraded the Restaurant Sector to Market Weight from Overweight, citing valuations and softening fundamentals. In addition, Applebee's International Inc. (NASDAQ: APPB) and P.F. Chang's China Bistro Inc. (NASDAQ: PFCB) were both downgraded to Underperform from Peer Perform.

• Following the lower-than-expected Q4 guidance, Morgan Keegan downgraded shares of Tellabs Inc. (NASDAQ: TLAB) to Market Perform from Outperform, as they do not expect a quick earnings recovery.

• Ensco International Inc. (NYSE: ESV) was downgraded to Underweight from Equal Weight at JP Morgan; the firm says there is growth risk to the global jackup market including overcapacity in early 2008.

Analyst summaries provided by TheFlyOnTheWall.com (subscription required).

The S&P 500 has announced several changes to the index. Ensco International (NYSE:ESV) is replacing BellSouth (NYSE:BLS). Cimarex (NYSE:XEC) will join the S&P Midcap 400. Hornbeck Offshore Services (NYSE:HOS) will join the Small Cap 600.

As the stocks are added to major indices, many index funds will be forced to buy them to stay current with the indices they track. Other "closet index funds" may add them as well. Should you?

If history is any guide, probably not. According to a piece in last week's Wall Street Journal [subscription required]: "... buy stocks that have been removed from the S&P 500. Those that suffered that indignity this year are up 27% on average since removal, while those that were added to the index are up only 1% since joining, notes Paul Hickey of Birinyi Associates."

While there were no stocks demoted in this group (BellSouth is no longer listed as it was acquired by AT&T.), the data would seem to suggest that investors may do well to avoid ESV and possibly HOS and XEC too.