In yuan terms, May trade data painted a different picture, with exports up 1.2 percent on-year and imports 5.1 percent higher.
The divergence with dollar figures reflected the interruption of the renminbi's long-term appreciation trend against the dollar, said Thierry Apoteker, executive chairman and chief economist at TAC Economics.
"China has been losing worldwide market share on manufactured products for a while... if worldwide trade in dollar terms is zero, China is at minus 4. This is no surprise because most competitors have had their currency depreciating by 20-25 percent since 2013, but the yuan has remained broadly stable, with depreciation only beginning since July 2015."
Indeed, simmering uncertainty about the direction of the renminbi has been the source of shaky investor sentiment.
Critics have long accused Beijing of manipulating its currency lower in order to benefit its exports, but the central bank has repeatedly denied those rumors as it attempts to let the currency become more market-oriented. On Wednesday, a People's Bank of China (PBOC) economist said the bank will allow the currency "some degrees of appreciation or depreciation" against a basket of currencies, Reuters reported.
But some banks such as OCBC are still anticipating a weaker currency on the back of a looming U.S. interest rate hike, not domestic policymaking. Goldman Sachs recently shifted to an "outright negative" view on the yuan, blaming the change in sentiment on a "weak link" in the mainland's currency management strategy.