CLOUD PEAK CORP

Prospectus Supplement for Delayed or Continuous Offering

Prospectus Supplement for Primary Offering

Automatic Shelf Registration

Automatic Shelf Registration

Prospectus Supplement for Primary Offering

Notice of Effectiveness

Prospectus Supplement for Delayed or Continuous Offering

Prospectus Supplement for Primary Offering

Post-effective amendment to an automatic shelf registration statement

Registration statement under Securities Act of 1933

Prospectus Supplement for Delayed or Continuous Offering

Automatic Shelf Registration

Prospectus Supplement for Primary Offering

Registration statement under Securities Act of 1933 (amendment)

Registration statement under Securities Act of 1933

Prospectus Supplement for Delayed or Continuous Offering

Prospectus Supplement for Delayed or Continuous Offering

Prospectus Supplement for Primary Offering

Prospectus Supplement for Primary Offering

Prospectus Supplement for Primary Offering

Prospectus Supplement for Primary Offering

Post-effective amendment filed solely to add exhibits

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7

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5,7

General form for quarterly reports under Section 13 or 15(d)

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5

Annual report pursuant to Section 13 or 15(d)

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5

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5

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7

5

General form for quarterly reports under Section 13 or 15(d)

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General form for quarterly reports under Section 13 or 15(d)

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5

General form for quarterly reports under Section 13 or 15(d)

5

Annual report pursuant to Section 13 or 15(d)

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General form for quarterly reports under Section 13 or 15(d)