By Nikhila Natarajan New York, Aug 19 : Digital ad spend may have turned the corner from March - April lows and current trends are pointing towards a "long promised" migration of dollars from the "$70 billion" television ad market to digital channels, with a 13 per cent year on year uptick expected in the second half of 2020 but on the back of higher costs and lower conversion rates, according to a report released on Tuesday from Bernstein Research, a Wall Street brokerage and research firm. "Digital ad spend appears to have turned the corner from March/April lows. We remain bullish on the sector," the report authors say. Digital's share of total ad spend in the US is expected to rise to 60 per cent in 2020, its highest in the last four years. The migration from linear television to digital is happening on the back of higher costs per action because of a tighter leash on retargeting. The report speaks of a 500 per cent increase in Cost Per Action and an 84 per cent decrease in Facebook conversion rates early July. Drawing on a recent survey by Interactive Advertising Bureau (IAB), the Bernstein research says ad buyers broadly appear poised to increase their digital ad spend. "It finally appears that the expected migration of TV dollars to digital may pick up momentum on the back of CTV/OTT spend and lack of original programming." During the 2020 second quarter, Facebook and Amazon gained ground by wading into Google's pie. Google, the report says, will claw back led by the return of hard-hit search verticals and continued improvement in YouTube ad products. "Net-net, Facebook and Amazon should continue to eat away at Google's share on the strength of eCommerce-related ad spend." This report comes at a time when the superstructure of online advertising is coming in for unprecedented scrutiny from lawmakers in the US and Europe in particular. Online advertising is headlined by the buying and selling of ad space through centralized electronic trading venues at high speeds, without people meeting face-to-face. Ad targeting headwinds "face a moment of truth", the report says. Bernstein is predicting slower user growth for big tech social platforms and "some impact" on players like Facebook Audience Network, Google's AdMob and Twitter's MoPub with in-app ad businesses. The report expects online time spent, which saw a bump in the first half of 2020, to "normalize" in the second half of the year. What's more interesting are the insights around new users' likely behaviour, post COVID. "With all the platforms continuing to invest in innovating their user product, we believe that the new users will likely stick around post pandemic," say the report authors. In the first half of this year, Facebook grew users by 15 per cent, Twitter delivered its "strongest user growth" of 34 per cent since it listed and Pinterest "significantly beat expectations" delivering a strong 39 per cent user growth. "Engagement levels should come down post COVID but likely land above pre-COVID levels." Twitter, the report says, is best positioned to retain users post-COVID "given the precedence set in Japan post-Fukushima." /IANS