The Oil and Gas Operations sector (DIG) is up 1.4%, outperforming the market overall. The biggest movers in the sector so far are:

Company | Market Cap | Percentage Change |

Whiting Petroleum Corporation (NYSE:WLL) | $4.65 billion | +3.9% |

Suburban Propane Partners, L.P. (NYSE:SPH) | $1.55 billion | -3.7% |

HollyFrontier Corp (NYSE:HFC) | $7.28 billion | +3% |

Clayton Williams Energy, Inc. (Nasdaq:CWEI) | $512.8 million | -2.8% |

Cimarex Energy Co. (NYSE:XEC) | $4.77 billion | +2.3% |

Sandridge Mississippian Trust I (NYSE:SDT) | $786 million | -2.3% |

Rosetta Resources Inc. (Nasdaq:ROSE) | $2.18 billion | +2.3% |

**Broker Summary: Fidelity Online Brokerage**

Increasing 3.9%,

**Whiting**(NYSE:WLL) is trading at $41.05 per share. So far today, 922,424 shares have changed hands. Volume is an important indicator because it indicates how significant a price shift is. Investors can make use of valuation ratios to estimate whether a stock is fairly valued. The price/sales ratio measures a company's stock market value by its total revenues or alternatively, a company's price per share by its revenue per share. WLL's P/S ratio of 2.38 is on the high side. This could be a good sign if the share price increases. A limitation of the P/S ratio is that the price component measures only stock market captialization, while sales are a function of the entire capital structure, potentially leading to wide differences between levered and unlevered companies.

**Suburban Propane Partners**(NYSE:SPH) is currently trading at a share price of $42.00, a 3.7% decline. The company's volume for the day so far is 88,843 shares, 0.7 times the current three-month average. As a stock moves up or down, it is important to pay attention to the trading volume. This indicates the level of interest: the higher the volume, the more the interest. A company's value as an investment is more easily estimated using valuation ratios such as the price to earnings (P/E) ratio, the price to earnings growth (PEG) ratio, the price to sales (P/S) ratio, the price to book (P/B) ratio, and the dividend yield. The debt ratio shows the proportion of assets that a company is financing through debt. SPH's debt ratio is 59.6%. However, one thing to note with this ratio: it isn't a pure measure of a company's debt (or indebtedness), as it also includes operational liabilities, such as accounts payable and taxes payable.

After an increase of 3%,

**HollyFrontier**(NYSE:HFC) has reached a current price of $36.26. The company is trading at a volume of 567,617 shares. This is on pace to fall short of yesterday's volume of 2.6 million shares. Price change alone is not enough to know how a stock is doing. Volume is an important secondary indicator used to confirm trends suggested by price movement. Valuation ratios include the price to earnings (P/E) ratio, the price to earnings growth (PEG) ratio, the price to sales (P/S) ratio, the price to book (P/B) ratio, and the dividend yield. The debt-equity (D/E) ratio compares the total liabilities for a company to its total shareholder equity. HFC's debt-equity ratio of 25% is on the low end. Companies with low D/E ratios are more attractive to investors because they are better able to protect their business interests in times of decline. The D/E ratio percentage provides a much more dramatic perspective on a company's leverage position than the debt ratio percentage.

**Clayton Williams Energy**(Nasdaq:CWEI) is trading at $41 per share, down 2.8%. So far today, the company's volume is 93,584 shares, 1.1 times the average daily volume. If a stock price makes a big move up or down, volume lets us know the significance of that move. When estimating the value of a particular investment, valuation ratios provide a good basis for assessing the value of an individual stock. The capitalization ratio is calculated by dividing long-term debt by the sum of long-term debt and shareholders' equity. The capitalization ratio for CWEI is 64%, which is fairly high. A high capitalization ratio is not necessarily bad since higher financial leverage can increase the return on a shareholder's investment. The capitalization ratio is one of the more meaningful debt ratios because it focuses on the relationship of debt liabilities as a component of a company's total capital base, which is the capital raised by shareholders and lenders.

**Cimarex**(NYSE:XEC) has risen 2.3% and is currently trading at $56.96 per share. So far today, the company's volume is 184,734 shares. A stock's volume conveys how excited investors are about it. It is important for an investor to estimate the value of any potential or existing investment; valuation ratios make this easier. The price/earnings ratio is calculated by taking a stock price and dividing it by the earnings-per-share (EPS). XEC has a P/E ratio of 9.0. To determine the P/E ratio, an investor divides the market price of the stock by the earnings-per-share (EPS) of the stock. SEE: Can Investors Trust the P/E Ratio?

Falling 2.3%,

**Sandridge Mississippian Trust**(NYSE:SDT) is currently at a share price of $27.43. At 83,684 shares, the company's volume so far today is in keeping with its current three-month average. If a stock price moves on high volume, this means that the change is a significant one. Investment valuation ratios can be very useful in estimating whether a stock price is too high, reasonable or a bargain investment opportunity. The price/book value ratio is calculated by dividing the current stock price by the company's book value per share. SDT's P/B ratio of 2.74 shows that its share price is higher than its book value. This may be a sign that the company is overvalued. A weakness of the P/B value ratio is that while the price component is easily determined by looking at the stock quote, the book value component is more difficult to estimate and more open to individual interpretation and analysis. SEE: How Buybacks Warps The Price-To-Book Ratio

**Rosetta Resources**(Nasdaq:ROSE) has risen 2.3% to hit a current price of $42.14 per share. The company's volume for the day so far is 190,612 shares. At this rate, trading activity will likely be down from yesterday when 970,741 shares changed hands. If a stock is trading on low volume, then there is not much interest in the stock. On the other hand, if a stock is trading on high volume, then there is a lot of interest in the stock. In making a decision about a potential or existing investment, valuation ratios are useful as a basis for seeing whether the stock price is too high, reasonable, or a bargain. The price/sales ratio measures a company's stock market price by its revenues. ROSE has a high P/S ratio of 5.52. In young companies, a high P/S ratio is a sign of sales growth that is expected to turn into earnings and cash flow. All things being equal, a low P/S ratio is good news for investors, while a very high one can be a warning sign.

**The Bottom Line**The nature of the market is such that stocks will have good days and bad days. Paying close attention to the previous ratios will help you identify key times to adjust your strategy. Tools like valuation ratios and profit margins, however, are only as useful as the context you put them in; remember to take historical data and competitor performance into account.