(Adds details on estimates)
NEW YORK, Feb 5 (Reuters) - Morningstar Inc said on Thursday its estimated net outflow for the Pimco Total Return for January was $12.5 billion, or 9 percent of end-December assets of $143.4 billion.
Morningstar said total assets in the Pimco Total Return Fund at the end of January were $134.6 billion.
Morningstar said it estimates open-end fund net flows by computing the change in assets from one month to the next that is not explained by the performance of the fund.
Pimco's actual flows may differ from Morningstar's estimates for a variety of reasons, including the timing of actual purchases and redemptions versus our assumptions and the timing and type of dividend distributions, for example, Morningstar said in a statement.
Pimco said on Tuesday that investors in January yanked $11.6 billion from its flagship Pimco Total Return Fund that had been overseen by Bill Gross, who left on Sept. 26. (Reporting by Jennifer Ablan; Editing by James Dalgleish and Grant McCool)