Is it the pent-up energy coming off the extended holiday weekend, or the several intriguing news items coming down the pike after market close?

Either way, trading is quite lively in the after-hours scene tonight. Here are two big reasons why.

Turkey gazing at the camera.

Image source: Getty Images.

Starboard boxes itself in

Noted activist hedge fund Starboard Value is now a major shareholder in tech stock Box (NYSE:BOX). In a regulatory document filed after market hours on Tuesday, Starboard revealed it has accumulated a stake of 7.5% in the cloud content specialist. 

In the filing, Starboard used boilerplate language to indicate its "belief that the Shares, when purchased, were undervalued and represented an attractive investment opportunity." The company did not further elaborate on its intentions with the stock.

Box was fairly mum on the subject, too.

A company spokesperson said to TechCrunch that "[w]hile we do not comment on interactions with our investors, Box is committed to maintaining an active and engaged dialogue with stockholders. The Board of Directors and management team are focused on delivering growth and profitability to drive long-term stockholder value as we continue to pioneer the Cloud Content Management market."

Typically, Starboard goes the activist route by taking significant stakes in companies and agitating for managerial and/or operational change. It may, however, simply consider Box shares to be undervalued. Box's stock recently set new one-year lows, and is barely above the $14-per-share price it sold for in its 2015 initial public offering (IPO). 

Box management might not be looking forward to Starboard's involvement, but investors seem to think this will be good for the shares: Box stock is up by 8% in after-hours trading.

Tyson gives 2019 EPS guidance the chop

Tyson Foods (NYSE:TSN) investors might be wishing for a Starboard to swoop down on their company just about now. The food producer and distributor updated its guidance for the entirety of its current fiscal 2019, and the downward revision is pushing its share price down.

For the year, the company now anticipates booking a per-share, non-GAAP (adjusted) net profit of $5.30 to $5.70.

This not only represented a cut to the previous guidance -- which was for $5.75 to $6.10 -- it also came in well below the average analyst estimate of $5.93 for the period.

Tyson said the reason for the downward revision is that "it is experiencing short-term challenges that are negatively affecting fourth quarter earnings."

Specifically, these involve "margin compression related to a reversal of a gain on mark to market grain derivatives recognized in our third quarter, commodity market volatility, implementation of enhanced food safety initiatives, a beef processing plant fire, and slower than expected operational improvements in the Chicken segment."

This development will likely slow or reverse the momentum of Tyson shares. These had been on quite the tear this year, thanks to moves such as a push into the trendy plant-based alternative-meat segment.

Tyson is a turkey of a stock tonight. It's down by nearly 6% as of this writing.

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