* JPMorgan, Wells Fargo, Citigroup gain after results
* Starbucks down after Cowen downgrade
* Futures: Dow 0.54 pct, S&P 0.53 pct, Nasdaq 0.44 pct (Adds comments, details, updates prices)
April 13 (Reuters) - U.S. stock index futures rose more than half a percent on Friday after a trio of big banks reported strong quarterly results, while geopolitical risks and concerns over trade war eased.
JPMorgan rose 1.5 percent in premarket trading after the biggest U.S. bank by assets reported a 35 percent surge in quarterly profit.
Wells Fargo rose 1.2 percent and Citigroup gained 1.6 percent after both the banks reported profit above Wall Street estimates.
"The numbers that we had were consistent with a strong economy," said Scott Brown, Chief Economist at Raymond James in St. Petersburg, Florida. "The mood is still very positive and investors are looking at good news over the bad news."
Tax cuts are expected to help corporate America post its biggest quarterly profit growth in seven years. Earnings at the S&P 500 companies are estimated to grow by 18.4 percent from a year earlier.
At 8:30 a.m. ET, Dow e-minis were up 131 points, or 0.54 percent and S&P 500 e-minis rose 14 points, or 0.53 percent. Nasdaq 100 e-minis gained 29.5 points, or 0.44 percent.
Stocks got a boost on Thursday after U.S. President Donald Trump cast doubt over the timing of his threatened strike on Syria, easing the risk of clashes between Western powers and Russia in Syria over an alleged chemical attack.
Talks of the United States re-opening negotiations with the Trans Pacific Partnership (TPP), a multinational trade deal the Trump administration walked away from last year, also helped sentiment.
But Trump later tweeted that the United States would only join the TPP if the deal were substantially better than the one offered to former President Barack Obama.
Among other stocks, Starbucks shares fell 1.2 percent after brokerage Cowen and Co downgraded the stock to "market perform."
Dropbox fell about 7 percent after brokerage Instinet started with "reduce" rating on the cloud-based storage firm.
Tesla jumped nearly 3 percent after its founder Elon Musk said the electric car maker will not need to raise any money this year as it will have positive cash flow and be profitable in the third and fourth quarter.
(Reporting by Sruthi Shankar in Bengaluru; Editing by Sriraj Kalluvila)