UPDATE 6-Oil turns negative after unexpected massive U.S. crude stock build

* U.S. crude stocks up 15.2 mln bbls,biggest build since
April-EIA
* U.S. net imports of crude oil rise by highest on record
* U.S. dollar falls to 2-1/2-year lows

(Updates prices, market activity, adds commentary; changes
byline, dateline, previous LONDON)
By Laura Sanicola
NEW YORK, Dec 9 (Reuters) - Oil prices fell about 1%
Wednesday, reversing strong gains after data showed U.S. crude
stockpiles jumped unexpectedly in their largest build since
April amid a record surge in imports.
U.S. crude inventories rose by 15.2 million barrels to 503.2
million barrels last week, according to the Energy Information
Administration, compared with analysts' expectations in a
Reuters poll for a 1.4 million-barrel drop.. EIA/S
Brent crude LCOc1 fell 21 cents, or 0.4%, to $48.63 a
barrel by 11:09 a.m. EST (1609 GMT). U.S. West Texas
Intermediate (WTI) crude CLc1> fell 39 cents, or 0.9%, to
$45.21.
"I'm trying to get my jaw off the ground here...15 million
barrels is an off-the-charts build," said Phil Flynn, senior
analyst at Price Futures Group in Chicago.
U.S. net imports of crude oil rose by 2.7 million barrels
per day last week, the biggest increase on record, as exports
plunged. EIA/S
"It looks like the Saudis are targeting the U.S. inventories
situation again, sending barrels here," said John Kilduff,
partner at Again Capital LLC in New York.
U.S. gasoline and distillate stockpiles were also markedly
higher as refineries boosted output.
"The significant increase in gasoline and distillate
inventories is likely a result of lower oil demand post the
Thanksgiving holiday, as well as additional stay at home
measures across country," said Andrew Lipow, president of Lipow
Oil Associates in Houston.​
Earlier in the session, oil rose as news about COVID-19
vaccines lifted investor hopes for a recovery in fuel demand and
the U.S. dollar, in which oil is traded, reached 2-1/2-year
lows. USD/ .DXY
Britain began mass vaccinations on Tuesday. Expectations
that others will soon follow helped offset fears about a sharp
rise in coronavirus cases globally that has led to new
restrictions on movements around the world. The vaccine news helped offset some fears from a sharp rise
in coronavirus cases globally that has led to a string of
renewed lockdowns, including strict measures in California,
Germany and South Korea.
"The worsening COVID situation, in particular in Europe, is
weighing on prices," research firm JBC Energy said.

(Addidtional reporting by Laila Kearney, Stephanie Kelly,
Jessica Resnick-Ault, Noah Browning and Yuka Obayashi; Editing
by Marguerita Choy and Bernadette Baum)