Where investors could find upside if the economy softens in the next six months.

Investors may want to consider bracing for a weaker stock market performance over the next six months.

According to Vanguard's Roger Hallam, it's prudent for long-term investors to have sufficient exposure to fixed income in this environment.

"Our outlook for the second half of this year is that growth will slow," the firm's global head of rates told CNBC's "ETF Edge" on Monday.

Hallam predicts the labor market will continue to gradually cool while inflation rises. Hallam expects the Federal Reserve will ultimately prioritize jobs and cut interest rates toward the end of this year to provide insurance.

"We think that will provide a tailwind for bonds," he said. "So, we're confident in the outlook for fixed income, and we think... clients should be allocating to fixed income."

Vanguard is behind three U.S. government bond exchange-traded funds debuting this week. The launch includes the Vanguard Government Securities Active ETF (VGVT).