Bank of America Global Research notes that historical evidence for a summer carry bias is relatively weak.

"Delivered vol does not exhibit a persistent decline through the summer, while seasonal effects in implied vol are relatively modest and appear to primarily reflect a mild compression in risk premia rather than a systematic decline in realized uncertainty. This suggests that successful carry environments are driven more by macro regimes than by the calendar itself," BofA notes.

"Taken together, the evidence points to a regime characterized by contained uncertainty, where investors continue to view the macro outlook as sufficiently predictable to favor carry-oriented positioning," BofA adds.