Ocean Rig UDW Inc.

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Certification of termination of registration of a class of securities (Section 12(b))

Notice of Effectiveness

Post-effective amendment to a registration statement

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Post-effective amendment to an automatic shelf registration statement

Notification of removal from listing and/or registration on a national securities exchange

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Written communication about a business combination transaction (Rule 425)

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Written communication about a business combination transaction (Rule 425)

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Written communication about a business combination transaction (Rule 425)

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

No description available

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Registration statement / Annual report / Transition report for Foreign Private Issuers

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Prospectus Supplement for Primary Offering

Report of foreign private issuer pursuant to Rule 13a-16 or 15d-16 under the Securities Exchange Act of 1934

Prospectus Supplement for Primary Offering

Prospectus Supplement for Primary Offering

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Prospectus Supplement for Primary Offering

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Correspondence with the SEC

Letter from the SEC

Beneficial ownership report for a holder of more than 5% (Schedule 13D)

Beneficial ownership report for a holder of more than 5% (Schedule 13D)

Beneficial ownership report for a holder of more than 5% (Schedule 13D)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Registration statement / Annual report / Transition report for Foreign Private Issuers

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Beneficial ownership report for a holder of more than 5% (Schedule 13D) (amendment)

Correspondence with the SEC

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Registration statement / Annual report / Transition report for Foreign Private Issuers

Letter from the SEC

Correspondence with the SEC

Beneficial ownership report for a passive holder of more than 5% (Schedule 13G) (amendment)

Letter from the SEC

Correspondence with the SEC

Letter from the SEC

Correspondence with the SEC

Letter from the SEC

Letter from the SEC

Letter from the SEC

Letter from the SEC

Letter from the SEC

Post-effective amendment to an automatic shelf registration statement

Registration statement / Annual report / Transition report for Foreign Private Issuers

Post-effective amendment to an automatic shelf registration statement

Letter from the SEC

Correspondence with the SEC

Registration statement / Annual report / Transition report for Foreign Private Issuers

Registration statement / Annual report / Transition report for Foreign Private Issuers

Registration statement / Annual report / Transition report for Foreign Private Issuers (amendment)

Registration statement / Annual report / Transition report for Foreign Private Issuers