US STOCKS-ECB measures lift Wall St in volatile session

* ECB President Draghi announces bond-buying program

* Verizon (NYSE: VZ - news) , American Express (Swiss: AXP.SW - news) both fall after results

* Royal Bank of Canada (Toronto: RY-PB.TO - news) to buy City National

* Indexes up: Dow 0.7 pct, S&P 0.8 pct, Nasdaq 1 pct (Updates to midday trading)

By Ryan Vlastelica

NEW YORK, Jan 22 (Reuters) - U.S. stocks rallied in volatile trading on Thursday after the European Central Bank announced expanded measures to stimulate the region's sagging economy, as expected.

Equities moved between positive and negative territory, with a number of disappointing corporate results from bellwether stocks spurring some morning selling.

The ECB will buy 60 billion euros worth of assets per month, an amount that was more than expected, in a program that will last through September 2016.

While U.S. stocks were volatile after ECB President Mario Draghi's news conference, shares in Europe jumped 1.5 percent.

"When you have every central bank in the world trying to stimulate the global economy, that's a tough thing for asset prices to fight against," said Wayne Kaufman, chief market analyst at Phoenix Financial Services in New York.

U.S. jobless claims fell from a seven-month high in the latest week, though the decline was less than expected.

Verizon Communications (Xetra: 868402 - news) fell 2.2 percent to $47.17 after swinging to a net loss in its latest quarter, while revenue rose 6.8 percent. The stock weighed on both the Dow index and on telecom stocks, which were by far the weakest sector of the day, down 1.6 percent.

American Express Co also weighed on the Dow, falling 3.1 percent to $85.03 a day after it said it would cut more than 4,000 jobs this year as expenses and provisions for bad loans rose.

F5 Networks Inc (NasdaqGS: FFIV - news) slumped 12.5 percent to $110.22 after the network equipment maker reported revenue that missed expectations for the first time in eight quarters. It also forecast current-quarter revenue and profit below market estimates.

On the upside, Travelers Cos Inc rose 1.4 percent to $106.52 after reporting a rise in net profit.

With 15 percent of S&P 500 components having reported, 73.7 percent have topped earnings expectations while 53.9 percent have beaten on revenue, according to Thomson Reuters data. That compares with the long-term average of 63 percent for earnings and 61 percent for revenue.

"We're satisfied with the earnings season, not disappointed or impressed," said Rex Macey, chief allocation officer at Wilmington Trust Investment Advisors in Atlanta (BSE: ATLANTA.BO - news) , Georgia.

"However, we're not seeing anything that looks like a screaming buy."

City National Corp jumped 19 percent to $88.41 after the Royal Bank of Canada said it would buy the company in a cash-and-stock deal valued at $5.4 billion.

At 12:26 p.m. (1726 GMT) the Dow Jones industrial average rose 128.44 points, or 0.73 percent, to 17,682.72, the S&P 500 gained 15.5 points, or 0.76 percent, to 2,047.62 and the Nasdaq Composite added 45.31 points, or 0.97 percent, to 4,712.73.

Advancing issues outnumbered declining ones on the NYSE by 2,199 to 770, for a 2.86-to-1 ratio on the upside; on the Nasdaq, 1,727 issues rose and 912 fell for a 1.89-to-1 ratio favoring advancers.

The benchmark S&P 500 index was posting 60 new 52-week highs and 5 new lows; the Nasdaq Composite was recording 32 new highs and 61 new lows. (Editing by Bernadette Baum and Meredith Mazzilli)