=+2. The monthly closing prices for VLO and TSO for the year 2005 are given in Table A.2.

(The closing prices are adjusted for stock splits and dividends.)

TABLE A.2 Monthly Closing Prices for VLO and TSO VLO TSO Date Adj . Close* Volume Adj . Close* Volume 3-Jan-05 25.89 6,327,590 31.71 1,156,805 1-Feb05 35.49 11,433,242 36.78 1,283,473 1 -Mar-05 36.5 14,312,645 36.87 1,496,781 l-Apr-05 34.14 19,363,771 I 37.79 1,944,952 2-May-05 34.24 15,281,285 43.48 1,586,209 l-Jun-05 39.47 11,828,418 46.39 1,481,663 l-Jul-05 41.3 11,438,900

! 48.09 1,213,225 l-Aug-05 53.2 18,753,469 57.69 1,948,447

]-Sep05 56.48 24,614,095 67.12 3,366,504 3-OcK35 52.57 23,972,552 1 61.04 3,137,700 1-Nov05 48.1 17,303,419 55.07 2,545,585 l-Dec-05 51.6 11,718,461 61.55 1,698,647 Source: http://finance.yohoo.com