Working with his financial advisor, John has a strategy to rebalance every quarter after initial investment to keep 60% stock and 40% bond portfolio. His initial investment is $100,000 and he put $60,000 in S&P 500 index fund and $40,000 in Vanguard Whole Market Bond Fund. After first quarter, his stock holding is worth $65,000 and his bond holding is worth $39,000. Please explain what actions he should take to rebalance his portfolio.