Gran Tierra Energy Set to Join Russell 3000 Index

Growth in Market Capitalization Results in Index Listing

CALGARY, Alberta, June 19 /PRNewswire-FirstCall/ -- Gran Tierra Energy
Inc. (Amex: GTE; TSX: GTE), a company focused on oil exploration and
production in South America, today announced that it is set to join the
broad-market Russell 3000(R) Index when Russell Investments reconstitutes its
comprehensive set of U.S. and global equity indexes on June 27, according to a
preliminary list of additions posted June 13 on http://www.russell.com.
Commenting on the matter, Dana Coffield, President and Chief Executive
Officer of Gran Tierra Energy Inc. stated, "Inclusion in the Russell 3000(R)
Index reflects the success of our Company. Our oil exploration and
development programs have resulted in reserves, production and cash flow
growth over the last year and a half, resulting in a material growth in our
market capitalization during that period."
Annual reconstitution of Russell's U.S. indexes captures the 4,000 largest
U.S. stocks as of the end of May, ranking them by total market capitalization.
Membership in the Russell 3000, which remains in place for one year, means
automatic inclusion in the large-cap Russell 1000(R) Index or small-cap
Russell 2000(R) Index as well as the appropriate growth and value style
indexes. Russell determines membership for its equity indexes primarily by
objective, market-capitalization rankings and style attributes.
The Russell 3000 also serves as the U.S. component to the Russell Global
Index, which Russell launched last year.
Russell indexes are widely used by investment managers and institutional
investors for index funds and as benchmarks for both passive and active
investment strategies. An industry-leading $4.4 trillion in assets currently
are benchmarked to them. These investment tools originated from Russell's
multi-manager investment business in the early 1980s when the company saw the
need for a more objective, market-driven set of benchmarks in order to
evaluate outside investment managers.
About Gran Tierra Energy Inc.:
Gran Tierra Energy Inc. is an international oil and gas exploration and
production company operating in South America, headquartered in Calgary,
Canada, incorporated in the United States, and trading on the American Stock
Exchange (GTE) and the Toronto Stock Exchange (GTE). The company holds
interests in producing and prospective properties in Argentina, Colombia and
Peru. The company has a strategy that focuses on growing a portfolio of
producing properties, plus production enhancement and exploration
opportunities to provide a base for future growth. Additional information
concerning Gran Tierra Energy is available at http://www.grantierra.com.
Investor inquiries may be directed to info@grantierra.com or
1-800-916-GTRE (4873).
Contacts:

Dana Coffield Al Palombo
Gran Tierra Energy, Inc. Cameron Associates
President & Chief Executive Officer Investor Relations
(800) 916-4873 (212) 245-8800 Ext. 209
info@grantierra.com al@cameronassoc.com

SOURCE Gran Tierra Energy Inc.

Dana Coffield, President & Chief Executive Officer of Gran Tierra Energy,
Inc., 1-800-916-4873, info@grantierra.com; or Investor Relations, Al Palombo
of Cameron Associates, +1-212-245-8800, ext. 209, al@cameronassoc.com, for
Gran Tierra Energy Inc.