Sure. The “institutions not buying this rally” is a general statement referring to the past couple of weeks as there is a noticeable drop off in volume to extremely low levels. Every morning at 9:30 am, no matter how low the recent volume trends are, once the opening bell rings at 9:30 am is when you see a sharp increase in volume (vs. the volume in the pre-market session leading right up to that point).
That is because the institution buyers step in as liquidity drastically improves during the regular session. In fact, trading volumes are usually highest immediately following the open & again leading into the close. If you pull an intraday chart (1-minute or 5-minute candles), you will see that the volume bars below resemble a smile: Highest after the open, tapering off around midday & then steadily increasing & peaking into the close.