The corporate sector normally runs a net funding deficit to invest; earnings so exceeded outlays that it swung to an unusual net surplus.

Analysts point to surging export receipts at major chipmakers while capital spending stayed relatively measured.

Part of the cash flowed into deposits and bonds. Rising corporate saving aids market liquidity short-term, but if it does not become investment, growth momentum could suffer, critics note.

Whether the semiconductor investment cycle restarts in the second half is seen as the biggest variable for corporate money flows.

Households' surplus funds shrank as home transactions rose—a stark divergence across sectors.