NEW YORK (CNNMoney.com) -- BP's stock jumped Wednesday after Fitch upgraded the company's rating three notches.
The upgrade came as the oil company released an internal report blaming the Gulf oil disaster on multiple causes.
Shares of BP (BP) rose more than 3% in morning trading.
Fitch upgraded the company's rating to 'A' with a stable outlook. That's up from its earlier 'BBB' rating. Both ratings are considered investment grade.
The ratings firm said the upgrade "primarily reflects an end to the threat of further leaks from the Macondo well in the Gulf of Mexico."
The BP-controlled well exploded on April 20, killing 11 workers on the offshore platform and unleashing a massive oil spill that caused catastrophic environmental and economic damage to the Gulf region.
"The 'A' rating also reflects both the improved visibility of potential liability scenarios the company could still face and substantial progress that BP has made to date in building up liquidity to address potential financial payments," said Fitch in a statement.
Fitch also cited U.S. Coast Guard commander Thad Allen's Sept. 4 declaration that the well had been "effectively secured regarding any potential source of pollution."
Separately, BP unveiled its report blaming the disaster on decisions made by "multiple companies and work teams" and was caused by "a complex and interlinked series of mechanical failures, human judgments, engineering design, operational implementation and team interfaces."
The company said the four-month report was conducted by more than 50 specialists from BP, along with external sources. 
| Index | Last | Change | % Change |
|---|---|---|---|
| Dow | 32,627.97 | -234.33 | -0.71% |
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| Treasuries | 1.73 | 0.00 | 0.12% |
| Company | Price | Change | % Change |
|---|---|---|---|
| Ford Motor Co | 8.29 | 0.05 | 0.61% |
| Advanced Micro Devic... | 54.59 | 0.70 | 1.30% |
| Cisco Systems Inc | 47.49 | -2.44 | -4.89% |
| General Electric Co | 13.00 | -0.16 | -1.22% |
| Kraft Heinz Co | 27.84 | -2.20 | -7.32% |
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