Following yesterday's heightened trading volumes, Valvoline Inc., National Oilwell Varco Inc, MPLX LP were the standout stocks.

Here's an update with information from the last trading session: Leading equity indices in the US declined as Dow Jones shed 0.8% and closed at 33,400. S&P 500 was down 0.7% before closing the session at 4,090.75.

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.

Though trading was down yesterday, some energy stocks reached high volumes. Here is an update.

Valvoline | 256% higher than rolling average

Trading volume peaked at 3.34 million shares yesterday, thereby obliterating the daily average of 1.31 million by 256%.

The automotive oil manufacturer is now trading 7.94% below the significant high of $37.03 it set around 2 months ago. The stock has been trending positively for about a month.

Valvoline is scheduled to announce earnings results Wednesday. The consensus Earnings Per Share estimate is 0.28 and the consensus revenue estimate is $344.36 million.

NOV Inc. | 191% above rolling average

NOV went down to $15.31 (1.67%), adding to its four days of losses. The hydrocarbon exploration enabler has fallen back around 37.22% from the significant high of $24.8 set 3 months ago. On a negative trend for around 30 days. The company has a market cap of $6 billion with an average daily volume of 4.81 million shares.

NOV Inc. outpaced its average daily trading volume (4.81 million) with 9.18 million shares traded yesterday.

MPLX | 212% higher than rolling average

With 3.38 million shares traded yesterday, MPLX beat its daily average by 212% to cap off a frenetic trading day.

The diversified master limited partnership is up 24.16% from the significant low of $28 it hit 10 months ago. The stock has been trending positively for about 4 months.

MPLX's board sets quarterly dividend of 77.5 cents per share to be paid on Monday, May 15th; annual dividend yield esimated at 8.87%.

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