Stocks were mixed on Wednesday, with the Dow Jones Industrial Average (^DJI 0.67%) mostly unchanged and the S&P 500 (^GSPC 0.87%) posting a loss.

Today's stock market

Index Percentage Change Point Change
Dow 0.09% 22.51
S&P 500 (0.28%) (8.12)

Data source: Yahoo! Finance.

Worries about the possibility of regulation dragged down internet stocks; the PowerShares NASDAQ Internet ETF (PNQI 1.06%) dropped 3.1%. Utilities had another good day, with the Vanguard Utilities ETF (VPU 1.04%) adding 1.2% to recent gains.

As for individual stocks, GameStop (GME -3.94%) rose on takeover rumors, and Sangamo Therapeutics (SGMO -0.27%) fell after reporting preliminary results from the first clinical trial evaluating in vivo gene editing in humans.

Up and down arrows over columns of numbers.

Image source: Getty Images.

Game on for GameStop

Shares of GameStop soared 15.7% on news that renewed investor hopes that the company will be taken private. The report from DealReporter, covered by an article in Bloomberg, says that private equity firms Sycamore Partners and Apollo Global Management are participating in a formal auction for the company.

GameStop is struggling to keep its business from shrinking as video games are increasingly sold through e-commerce channels or as downloads, rather than through physical stores. Last quarter, revenue fell 5.5% on a comparable-store sales decline of 5.3%. For the full year, GameStop expects sales to decline between 2% and 6%.

The company's stock price has been all about buyout prospects in recent months, with the company confirming last June it was in "exploratory discussions" with third parties about a potential transaction, and the stock plunging last week after a report that investors were "losing hope" that a deal was going to happen.

GameStop is scheduled to announce earnings tomorrow, so investors may finally hear definitive news, and with GameStop being one of the most-shorted stocks on the New York Stock Exchange, there is likely to be a big move in the share price -- one direction or the other.

Sangamo falls after reporting on landmark gene-editing trial

Gene-editing biotech pioneer Sangamo Therapeutics made history today by reporting clinical data from the first in vivo study of a genome-editing treatment in humans, but investor concerns about the results sent the stock tumbling 23.6%.

The ongoing study, called Champions, is testing Sangamo's SB-913 treatment for mucopolysaccharidosis type II (MPS II), or Hunter syndrome. Patients with MPS II have a gene mutation that causes a deficiency of an enzyme called iduronate 2-sulfatase (IDS). Lack of the enzyme causes a dangerous buildup of the complex sugars called glycosaminoglycans (GAGs), which can result in organ damage and death. SB-913 is a single intravenous infusion that uses Sangamo's gene-editing technology to repair the DNA of cells in the liver, enabling them to start producing the IDS enzyme.

The ongoing study is testing three dose levels of SB-913, and today's announcement reported 16-week results from the two patients each in the low-dose and middle-dose cohorts. The results showed little benefit to the low-dose patients, but the medium-dose cohort had a decrease in the harmful GAGs in their urine of over 50%. No patients had any serious adverse events related to the treatment.

What got observers concerned was the news that expected higher levels of the IDS enzyme were not measured. But Sangamo officials maintain that the reduced levels of GAGs indicate that the therapy is working and that their technique for measuring enzyme levels may simply not be sensitive enough to detect a change. 

More information will come with the results from the high-dose patients, who are receiving five times the dose as the medium-dose cohort. But although the test results were an historic step in the right direction, investors wanted to see stronger confirmation of efficacy, and the stock erased some of the gains it made running up to today's anticipated announcement.