On paper, the S&P 500 notched a new all-time high on Thursday... although this came from only a marginal improvement on the index. Looking at the bigger picture, it was really just another flat day from the stock market. This has become a pattern this week.

Even some of the frequently volatile tech stocks on the various exchanges didn't budge all that much in price. There weren't all that many outliers -- however, I've found two stocks in the sector that saw more lively action... albeit of the bearish variety. Here's a closer look at the pair.

Man holding his head, looking at a chart indicating losses.

Image source: Getty Images.

Cisco Systems

Woe betide any major publicly traded company that trims its guidance. This applies particularly to tech stocks, since investors in the sector often expect ever-rising growth rates even from the most mature businesses.

This is basically what happened on Thursday to long-established networking giant Cisco Systems (NASDAQ:CSCO), whose stock closed more than 7% lower. The company released its Q1 of fiscal 2020 results; within them the company proffered guidance indicating a year-over-year sales slowdown of 3% to 5% for its current Q2. 

News of the anticipated decline overshadowed what wasn't a bad Q1 at all. Both revenue and non-GAAP (adjusted) net profit rose, by nearly 1% and 5%, respectively, to $13.2 billion and $3.6 billion. The latter figure worked out to $0.84 per share. Both headline numbers were a bit higher than the average analyst estimates.

Although the anticipated Q2 sales slump won't necessarily be Cisco's fault -- the company accurately pointed out that many clients are reining in spending on networking equipment due to economic uncertainty -- it isn't helping investor sentiment.

For the most part Cisco has done a good job over the years growing its top line, if not all that dynamically, and keeping its margins nice and high. It can be uncomfortable to be invested in such a stock during a down quarter.

I'm a Cisco bull, as we're in an environment where the long-term need for reliable networking equipment is only going to grow throughout the world, especially in the enterprise segment. Yes, a dip in sales is a concern, but this is a bug and not a feature with Cisco. I'd consider buying the stock at a discount after Thursday's sell-off.

Weibo

A much steeper fall on the day was recorded by Chinese social network powerhouse Weibo (NASDAQ:WB), which saw a nearly 18% drop.

Weibo's problem was much like Cisco's -- guidance. Along with its Q3 of fiscal 2019 results unveiled in the morning, Weibo served up a weak revenue outlook for its current frame.

The trailing performance was Cisco-ish, in that Weibo demonstrated decent if unspectacular growth and lightly exceeded analyst projections. Q3's top line was 2% higher, clocking in at the equivalent of $468 million, although quite a bit of this growth was due to the consolidation of Yizhibo, a video streaming purveyor the company acquired in late 2018.

Meanwhile, adjusted net profit saw a 3% lift to just over $176 million ($0.77 per share).

For the current Q4, however, Weibo anticipates only flat-to-3% growth in its revenue on a constant-currency basis. At this point it almost goes without saying that this basically lands below analyst estimates for the quarter. Again, no investor likes guidance that comes in under expectations -- and shareholders of tech stocks tend to be awfully growth-hungry.

But there are other, quite justified, concerns here.

Ad-sales-dependent Weibo has seen a marked decline in revenue growth over only the last few quarters. And with the U.S.-China trade war and its effects on the Asian giant's economy -- which was looking relatively wobbly to begin with -- I can't imagine Chinese advertisers will suddenly and dramatically start opening their wallets again.

A 17%-plus chop in share price is quite drastic, and I imagine Weibo will attract some bottom-feeders. But I think this company is in for more struggle, so even at this level I think it's best to stay away from its stock at the moment.