Despite the Dow Jones Industrial Average and S&P 500 hitting intraday highs Friday, the markets took an abrupt downturn, thanks in large part to the technology sector, which ended hopes of the S&P 500 logging a weekly gain. However, the Dow managed to post a modest 0.31% move higher.

Across the pond, major European benchmarks closed higher Friday as expectations rose that the U.K. will seek a less devastating form of its European Union exit plan -- which is broadly good news for the world. There were also plenty of interesting moves from individual stocks last week. Here are some highlights.

Oh, Snap

It wasn't a thrilling week for shares of Snap (NYSE:SNAP), which started its downturn on Thursday after Anthony DiClemente, analyst for Nomura Instinet, released a bearish research note. And as we know, when it rains it pours: The bearish note was followed by a price cut by JPMorgan, and then a downgrade by Citigroup. Investors' reaction to the negative news sent shares down about 15% for the week, dipping dangerously close to record lows.

The focus of the bearish note was slower growth in the face of strengthening competition from Facebook. Per DiClemente's note: "An analysis of app download data from SensorTower points to YoY deterioration in Snapchat download trends through the first two months of 2Q17. By comparison, Instagram downloads have demonstrated YoY growth, suggesting that competitive pressures may be intensifying for Snap, challenging the platform's ability to attract and retain new users."

But there are more than just user-growth concerns for this young company. An additional red flag was raised when Snap's management pointed out that a sequential decline in revenues during the first quarter was caused by seasonality in the company's advertising business. Seasonality isn't generally a problem for investors, as that's priced into the stock, but Snap is such a young company that explosive growth shouldn't be an issue that's completely offset by seasonality. That's more of a problem for older, slower-growing companies.

It's far too early to draw any conclusions, but as far as stocks go, Snap appears to be closer to a struggling Twitter than a thriving Facebook.

Pop and drop

Over the past year or so, the retail industry has been synonymous with a couple of things: store closings and bad earnings reports. And for the most part, retail stocks have been pummeled in the process, including Macy's Inc. (NYSE:M), which sank lower last week after management warned its second-quarter gross margins are likely to be weaker than expected.

More specifically, Macy's Chief Financial Officer spoke earlier last week at an investor meeting and noted that gross margins were likely to decline 60 basis points to 80 basis points compared to the prior year's second quarter. That's similar to the first-quarter's 100 basis-point decline, compared to the prior year.

Woman standing in a clothing store.

Image source: Getty Images.

On the flip side last week was Nordstrom Inc. (NYSE:JWN), which recorded a near 11% rise during intraday trading Wednesday. The driving force behind its surge was a rumor that a group that includes co-presidents Blake and Peter Nordstrom has formed to potentially take the company private. While Nordstrom's gain has held through the back end of the week, there hasn't been a formal proposal -- which means there's no clue as to what premium could be paid for the outstanding shares.

The race is on

Investors of bluebird bio (NASDAQ:BLUE) had a great week, as shares of the clinical-stage biotechnology company soared more than 30%. The good news came Tuesday after the company presented early-stage data for its cancer treatment bb2121. The treatment takes immune cells from a patient and essentially trains the cells to attack cancerous cells with a protein named BCMA, before giving them back to the patient.

The results appear promising, according to my colleague Brian Orelli:

In an early stage, phase 1 trial of patients with multiple myeloma, bb2121 produced a 100% overall response rate at the three highest doses of treatment. Of the 15 patients, four of them achieved a complete response, seven of the patients were deemed to have a very good partial response -- that's an actual clinical term, not something Bluebird and Celgene made up -- and the remaining four had a partial response. The response rate is quite impressive considering that these patients had failed a median of seven prior therapies.

Despite the impressive results, the company now essentially enters a race against time, as there appears to be competition from Nanjing Legend Biotech, a Chinese company developing a similar BCMA attacking treatment.

Daniel Miller has no position in any stocks mentioned. The Motley Fool owns shares of and recommends bluebird bio, Facebook, and Twitter. The Motley Fool recommends Nordstrom. The Motley Fool has a disclosure policy.