An S&P 500 ETF is trading at a 20 basis point premium to its NAV during a morning rally. Walk me through the exact steps you would take as an Authorized Participant (AP) to capture this arbitrage. Where is your execution risk?

早盘大涨时，某标普500 ETF的价格比其净资产价值（NAV）溢价了20个基点。作为授权参与者（AP），请详细说明你要怎么做才能吃掉这个套利空间？风险在哪？