@joe74 posted some of what I was constructing below, though I may still be filling in a little:
"
other EM debt local currency funds". Is either fund primarily invested in unhedged, locally denominated debt?
Vanguard says of its fund that "the majority of bonds are expected to be invested in in U.S. dollar-denominated bonds or hedged back to the U.S. dollar. "
Meanwhile, until this month, Matthews benchmarked MAINX against the Markit iBoxx Asian Local Bond Index. According to the
fund prospectus, Mathews just changed the fund's benchmark to 50% of this index, and 50% of J.P. Morgan Asia Credit Index, which is
dollar-denominated. That seems to suggest that the fund had been invested primarily in local currency bonds but has recently moved closer to a 50/50 mix (currently
54% in US dollars).
With international investments, currency movements can play such a large role in performance that much of the difference between funds can be explained by this alone. I'm not saying that's the case here. Rather the suggestion that these are local currency funds invites checking further into how accurate that is.
Other notable differences:
Vanguard is virtually all sovereign debt; Matthews is 20%. (From M*'s new portfolio pages for the funds.)
Most of the Matthews fund is invested in east/southeast Asia, with the remainder (
19%) in south Asia (India, Sri Lanka), while little of Vanguard's fund is in either east/southeast Asia (5% in Indonesia, 2% in China) or south Asia (
1% in India). The little exposure that Vanguard has in Asia comes from central Asia (a couple of "stans"), and from the Asian countries of the Middle East (Saudia Arabia, Bahrain, etc.). Very different regions.
Maybe Vanguard alters its mix depending on the investment climate, or maybe these are geographically complementary funds.
A quick check of (semi) annual reports suggests that the Vanguard fund has had consistently little interest in east/southeast/south Asia aside from Indonesia (4% - 8%).
March 31, 2016 reportSept 30, 2016 reportMarch 31, 2017Sept 30, 2017 reportMarch 31, 2018 reportSept 30, 2018 reportMarch 31, 2019 reportSept 30, 2019 report