みんかぶの正規表現は、これじゃダメなの？

var valid = new Regex(
@"<td class=""tal"">(?<year>\d{4})/(?<month>\d?\d)/(?<day>\d?\d)</td>\r\n" +
@"<td class=""num"">(?<open>[0-9,.]+)</td>\r\n<td class=""num"">
(?<high>[0-9,.]+)</td>\r\n<td class=""num"">(?<low>[0-9,.]+)</td>\r\n<td class=""num"">(?<close>[0-9,.]+)</td>\r\n" +
@"<td class=""num"">.*</td>\r\n<td class=""num"">(?<volume>[0-9,]+)</td>");