The Transportation sector (IYT) is down 0.5%, underperforming the market overall. The current biggest movers in the sector are:

Company | Market Cap | Percentage Change |

Mobile Mini Inc (Nasdaq:MINI) | $649.3 million | +16.8% |

Allegiant Travel Company (Nasdaq:ALGT) | $1.34 billion | -5.6% |

Huntington Ingalls Industries Inc (NYSE:HII) | $1.99 billion | +3.3% |

Copa Holdings, S.A. (NYSE:CPA) | $3.52 billion | -3% |

Spirit Airlines Incorporated (Nasdaq:SAVE) | $1.49 billion | -3% |

Teekay Corporation (NYSE:TK) | $2.24 billion | -2.5% |

AMERCO (Nasdaq:UHAL) | $1.88 billion | -2.3% |

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**Mobile Mini**(Nasdaq:MINI) rose a significant 16.8% to reach $16.59 per share. The company is trading at a volume of 523,400 shares. This is more trading activity than there was yesterday. 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. 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 is a measurement of how much suppliers, lenders, creditors and obligors have committed to the company versus what the shareholders have committed. MINI's D/E ratio is 89%. This easy-to-calculate ratio provides a general indication of a company's equity-liability relationship and is helpful to investors looking for a quick take on a company's leverage.

Slipping 5.6%,

**Allegiant Travel**(Nasdaq:ALGT) is currently trading at $66.18 per share. At 68,065 shares, the company's volume so far today is in keeping with its current daily average. If a stock price moves on high volume, this means that the change is a significant one. Valuation ratios allow the investor to make a quick determination as to a company's investment value. As with most ratios, comparisons of company price/earnings to growth ratios (PEG ratios) are most appropriate for similar companies. ALGT's PEG ratio is 0.78. While P/E ratios are important indicators of market value, a high P/E in and of itself is not bad because it may indicate a company whose earnings are growing very rapidly, so many investors look at the PEG ratio in order to get an idea of whether or not a particular P/E ratio is justified by underlying earnings growth.

**Huntington Ingalls Industries**(NYSE:HII) is up 3.3% to reach a current price of $41.57 per share. This morning, the company is trading a volume of 144,212 shares. When a stock price moves up or down, watching the volume is a good way of identifying how significant that shift is. 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 price/book value ratio, often expressed simply as "price-to-book", provides investors a way to compare the market value, or what they are paying for each share, to a conservative measure of the value of the firm. HII's stock is trading for more than its book value with a P/B ratio of 2.24. It is important to take the company's debt into account when using the P/B ratio as debt can boost a company's liabilities to the point where they wipe out much of the book value of its hard assets, creating artificially high P/B values. All else being equal, a stock with a low P/B value ratio is more attractive than a stock with a high ratio. SEE: Using The Price-To-Book Ratio To Evaluate Companies

**Copa Holdings**(NYSE:CPA) has hit a share price of $76.99. With 380,251 shares changing hands so far today, the company's volume is 1.5 times its current three-month average. Volume is also used as a secondary indicator to help confirm what the price movement is suggesting. Looking at a company's valuation ratios is a good way of getting a basic idea as to its value as an investment. Dividend yield measures the income that a stock will generate for an investor. CPA's dividend yield is 2.6%. Simply comparing the level of dividends that two stocks pay does not give a true reflection of which security is more attractive, so investors calculate the dividend yield in order to standardize dividend payments. SEE: Investment Valuation Ratios: Dividend Yield

**Spirit Airlines**(Nasdaq:SAVE) is trading at $19.89 per share, down 3%. The company's volume for the day so far is 146,337 shares. This is on pace to fall short of yesterday's volume of 686,526 shares. Volume is an important indicator in technical analysis as it is used to measure the worth of a market move. If the markets have made a strong price move either up or down the perceived strength of that move depends on the volume for that period. The higher the volume during that price move the more significant the move. Valuation ratios like 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 are useful in determining how attractive a potential or existing investment is. A price/sales ratio is derived by dividing stock market price by company sales. SAVE's P/S ratio of 1.17 is on the high side. In young companies, a high P/S ratio is a sign of sales growth that is expected to turn into earnings and cash flow. 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.

At $31.57,

**Teekay**(NYSE:TK) has slipped 2.5%. The company's volume is currently 190,131 shares for the day, in line with the current daily average. Volume indicates the level of interest that investors have in a company at its current price. A company's investment value can be 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 easy-to-calculate debt ratio is helpful to investors looking for a quick take on the leverage for a company. TK's debt ratio of 87.5% is fairly high. As such, the company is highly leveraged and not highly liquid. As with all financial ratios, a company's debt ratio should be compared with the industry average or similar companies.

**AMERCO**(Nasdaq:UHAL) is down 2.3% to reach $93.50 per share. So far today, the company's volume is 15,513 shares. A stock's volume conveys how excited investors are about it. Understanding investment valuation ratios allows an investor to assess the true value of an individual stock. Perhaps one of the most widely-used stock analysis tools is the price-to-earnings ratio, or P/E. UHAL's P/E ratio of 9.4 is consistent with the industry average. From the investor's perspective, a stock with a lower ratio is relatively cheaper than a stock with a higher ratio. SEE: How To Use The P/E Ratio And PEG To Tell The Future Of A Stock

**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.