Nobody told Google (NSDQ: GOOG) Finance (it still doesn’t have the updated stock ticker), but Thomson Reuters‘ new TRIL.L listing started trading on the London Stock Exchange at 8am GMT, after their £8.7 billion ($17.1 billion) merger - and immediately fell 80p. The stock recovered after falling from the opening 1,700p per share to hover around 1635p after its first hour.

From the market announcement: “It is proposed that the nominal value of each ordinary share of Thomson (NYSE: TOC) Reuters (NSDQ: RTRSY) Plc be reduced by 975p from £10 to 25p. It is currently expected that, subject to court approval, such reduction will become effective on April 22, 2008.” Perhaps the stock symbol is apt for a newswire that started by using pigeons to fly stock quotes around central Europe (Trill is a bird food).

Reuters News editor-in-chief David Scheslinger, from the company’s blog: “Over the next weeks and months, we will combine the best from the old Reuters news and from Thomson Financial news; we’ll be bringing together people and services. Most of the difference will be seen immediately on our desktop products for financial professionals, but over time I’m sure you’ll see new bylines and data on our Reuters Media consumer-facing sites as well.”

Formerly headquartered in London, the new Thomson Reuters, with $12.5 billion revenues, is now based in New York, where its TRI (NYSE) and TRIN (Nasdaq) stock will open later along with another TRI in Toronto. But Reuters retains its significant presence in the UK and Minnesota. Reuters.co.uk remains badged “Reuters UK”, albeit with a new masthead.

Bloomberg, conceding TR “will rival (us) as the largest financial-information provider with 32.27 percent of the market”: CEO Tom Glocer said job cuts are not the priority but reiterated a goal of $500 million savings after three years, conceding: “We have a Noah’s Ark of two of a bunch of things.”

Glocer (via Reuters) on the eve of the merger, suggested Thomson Reuters is no News Corp (NYSE: NWS). “We are not going to own a film studio. We are not going to launch a teenage social networking service. We’re really focused only on professionals, people who will pay us for our content and services.”

So who are the competitors? Glocer said Google monetised primarily “consumer content” and the “low end of professional”. “News Corp-Dow Jones has a potential seat at the table ... Microsoft-Yahoo (NSDQ: YHOO) does if they pull it off merge and if Microsoft (NSDQ: MSFT) embraces content more than it has before.” “There are going to be a handful of ‘information majors’ - we’re all going to compete in some areas, cooperate in some others.”

Update: Gorkana: “All Reuters and Thomson Financial journalists now have new emails: .”

Update 2: TRI.L closed in London down at 1,560p from the opening 1,700p.

• Thomson Reuters Day One: Combined Company, New Logo
• Earnings: Reuters’ 07 Profit Dips On Home Strait To Thomson Merger