Picking Values from variable range

Hello,

I have a problem. From the attachment (same in message body in case attachment is not there) you can see I have a data. This data is for ~10 years. It is daily data. I need to pull week's opening value, week's closing value and maximum and minimum value of the week. Week is from Monday to Sunday. But due to holidays, number of days in a week and first day of the week itself are not consistent. I need to do the same for calendar month, pull out monthly values. How can I do it fast and using a formula?

By using =IF(C7="Friday",IF(C6="Thursday",IF(C5="Wednesday",IF(C4="Tuesday",IF(C3="Monday",1,0))))) I was able to identify full working weeks and copy paste my calculation formula for these weeks. But for balance weeks and months I can't.

Please advice.

Thanks,
Elaine

Day Date Open High Low Close
Monday 3-Nov-08 582.3 624.7 580.05 602.2
Tuesday 4-Nov-08 600 648.9 582.4 640.45
Wednesday 5-Nov-08 651.9 674.8 592.35 604
Thursday 6-Nov-08 590 610.9 552.5 582.7
Friday 7-Nov-08 580 599 547.15 581.6
Monday 10-Nov-08 594.45 613 578.3 608.9
Tuesday 11-Nov-08 600 603 560 564.05
Wednesday 12-Nov-08 559 569.7 523.15 525.3
Friday 14-Nov-08 540 554.4 487 492.95
Monday 17-Nov-08 587.2 587.2 431.3 456.65
Tuesday 18-Nov-08 452 452 425 437.75
Wednesday 19-Nov-08 425 464.3 421.1 427.55
Thursday 20-Nov-08 418 418 394 405.45
Friday 21-Nov-08 419 422.5 383.6 411.5
Monday 24-Nov-08 409 420 391.85 397.55
Tuesday 25-Nov-08 414.8 418.7 367 376.55
Wednesday 26-Nov-08 379.9 418.2 362.4 404.45
Friday 28-Nov-08 382 416 352.5 408.5
Monday 1-Dec-08 412.5 436.7 408.1 413.05
Tuesday 2-Dec-08 408 434.7 388.25 429.1
Wednesday 3-Dec-08 435 439.9 422.4 433.7
Thursday 4-Dec-08 439.5 464.8 433 455.2
Friday 5-Dec-08 457 475 440 443.05
Monday 8-Dec-08 460 468 448 451.95
Wednesday 10-Dec-08 457.4 466 438.15 462.8
Thursday 11-Dec-08 465.5 479 444.4 457
Friday 12-Dec-08 449.7 473.4 435.6 468.8
Monday 15-Dec-08 478.2 492.4 475 486.2
Tuesday 16-Dec-08 485 506.3 478.25 500.8
Wednesday 17-Dec-08 504 520 492.05 497.6
Thursday 18-Dec-08 495 543 495 537.2
Friday 19-Dec-08 539.7 562 531.25 546
Monday 22-Dec-08 549.7 556.8 528.55 537.5
Tuesday 23-Dec-08 533.1 542.9 490.75 499.5
Wednesday 24-Dec-08 495 498 481 490.75
Friday 26-Dec-08 491.45 511 477.25 482.8
Monday 29-Dec-08 480 501.8 468 494.95
Tuesday 30-Dec-08 496.5 519.4 494 510.25
Wednesday 31-Dec-08 519.7 521 499.6 504.7
Thursday 1-Jan-09 508.5 522.7 508 516.85
Friday 2-Jan-09 522 547.5 517.3 541.9
Monday 5-Jan-09 549.5 564.8 549.5 560.1
Tuesday 6-Jan-09 561 577 551.4 569.75
Wednesday 7-Jan-09 574 575.4 515 522.1
Friday 9-Jan-09 508 540.3 475 486.6
Monday 12-Jan-09 490 494.8 445 451.7
Tuesday 13-Jan-09 442 465 433 440.3
Wednesday 14-Jan-09 450 456.95 438 449.4
Thursday 15-Jan-09 430 438.4 421 434.05
Friday 16-Jan-09 448.7 451 436 443.55
Monday 19-Jan-09 448.9 450 431.55 438.3
Tuesday 20-Jan-09 429.7 429.7 416.6 422.4
Wednesday 21-Jan-09 405.55 428 404 407.7
Thursday 22-Jan-09 410.5 421 403.3 416.05
Friday 23-Jan-09 410 418.9 380.1 384.3
Tuesday 27-Jan-09 394.95 404.7 383.25 394.75
Wednesday 28-Jan-09 399 429.5 397 422.85