Calm waters presented 3 heavy volume marlins in stocks Friday

A busy day for HollyFrontier Corp, Cabot Oil & Gas Corp, Valero Energy Corp, being the prominent energy stocks displaying higher volumes than usual.

Here's an update with information from the last trading session: Markets did not have a clear cut direction — Nasdaq closed at 12,072 after a flat day. Dow Jones closed 33,800 after a stable day.

Why trading volume matters?

Trading volume is simply the total number of shares traded including both buy and sell orders. If a stock has appreciated on high volume, it is more likely to be a sustained move compared to an appreciation with low volume. Typically, high volume trading sessions are considered significant occurrences and closely watched by traders.

While trading was mostly sideways Friday, several energy stocks were actively traded. Here's an update:

HollyFrontier | 119% slightly above rolling average

HollyFrontier Corp rose 71 cents to close at $36.39 Friday which makes for a move of 2%.

With 4.78 million shares traded Friday, HollyFrontier beat its daily average by 119% to cap off a frenetic trading day.

Cabot Oil & Gas Corp | 219% above rolling average

Trading volume was 18.76 million shares Friday — beating the daily average by a mammoth 219%.

Valero | 156% higher than rolling average

Valero went down to $119.63 (2.7%), adding to its nine days of losses. The energy company has fallen back around 18% from the significant high of $149.96 set 2 months ago. The Fortune 500 petroleum refinery operator's market cap currently stands at $44 billion with an average daily volume of 4.27 million shares.

Friday's trading volume was 6.64 million shares (surpassing the daily average by 156%).

— Average trading volume refers to a 21-day rolling average.