The jury’s still out on whether ad blocking will help or hurt the expansion of programmatic advertising, a survey of U.S. marketers has found. Wall Street has expressed off-and-on concern that Apple ‘s ( AAPL ) decision to let users install apps that prevent ads from appearing in its Safari mobile browser could cut into the business of ad-tech companies, but an industrywide decline has not materialized. A March survey by investment bank RBC Capital Markets and Advertising Age found that 58% of respondents believe ad-blocking technology will have a “somewhat negative” effect on the programmatic advertising ecosystem. Another 20% of respondents said ad blocking will have a “significantly negative” effect on the programmatic advertising space, said the survey, which was reported by research group eMarketer on Wednesday. Still, some marketers believe ad blocking could be good for programmatic, with 6% of the marketers surveyed saying ad blocking would have either a “significantly positive” or “somewhat positive” effect on automated ad buying. Even so, some senior ad buyers in the U.S. are bracing for trouble as programmatic advertising expands. The RBC survey found that 57% of ad buyers listed multidevice measurement as a problem for programmatic, followed by fraud (47%), ad blocking on smartphones (35%) and privacy issues (18%). Gaming, social networking and tech-related websites are said to be most affected by ad-blocking software. Gaining Steam Seven months after Apple made ad blocking possible on iOS mobile phones , eMarketer says that the trend is gaining steam. That could mean companies including Alphabet ( GOOGL ) search unit Google, French ad firm Criteo ( CRTO ) and others that rely on advertising to make money aren’t totally in the clear, though they’ve said that ad blocking isn’t affecting their business. Ad sales conducted by machines rather than ad salespeople — so-called programmatic ads — take less time to execute and cost advertisers less, which accounts for their popularity with advertisers, though it tends to lower revenue for online-ad platforms. Ad blockers serve to reduce the amount of bandwidth that a user needs by cutting down the amount of content — seen and unseen — that a page has to load. They can also help with privacy by blocking programs that track users’ browsing habits — good for users, bad for advertisers who want to show their ads to people who are the most likely to buy their products. Mobile is driving programmatic advertising growth, with mobile accounting for more than two-thirds of all programmatic digital display-ad spending this year, says eMarketer in a report on Tuesday. Facebook ( FB ), Google-owned YouTube, LinkedIn ( LNKD ) and others are helping to drive the trend. Declining Growth Rate U.S. programmatic digital display-ad spending is projected to rise to $27.4 billion in 2017, up 24%, eMarketer said last week. But that growth rate is declining from a projected 39% this year and 53% in 2015, the research group said. Mobile programmatic spending will reach $15.45 billion in the U.S. in 2016, representing 69% of all programmatic digital display-ad spending, according to eMarketer. That’s up from 60% in 2015 and 46% in 2014. Apple stock climbed 1% in midday trading in the stock market today , near 112, and is up more than 20% since touching an eight-month low early this year. Alphabet stock rose by a fraction, near 770 and approaching a cup-with-handle breakout buy point at 777.41.