bboo

Text reads " ..approximation methods such as Modified Dietz and Modified IRR will not meet the GIPS standard for period after 1 Jan 2010, when firms will be required to value portfolios on the date of all large external cash flows."

My understanding is use TTWR for cases after 1/1/10. To facilitate use of TTWR firms are required to value portfolio on dates of large external cash flow. If cash flows are not large, firms would not have valued their portfolio on those dates, so we can conveniently ignore the 'not-large' cash flows. But not to use Modified Dietz unless specified.