By Claire Milhench

LONDON, May 18 (Reuters) - Sovereign wealth funds pulled $18.4 billion from global stock and bond markets in the first quarter of 2017, notwithstanding robust equity gains in this period, data from research firm eVestment showed on Thursday,

Oil-backed sovereign wealth funds (SWFs) have been under pressure since oil prices LCOc1 tumbled from their mid-2014 highs of $115 to around $52 a barrel, with governments tapping state funds to close budget gaps.

Global SWF assets effectively stalled at $6.59 trillion in the 12 months to March 2017, data from research firm Preqin showed in April, due to a combination of weak markets, low oil prices and shifts in government policy.

The latest figures from eVestment, which collates data from around 4,400 firms managing money on behalf of institutional investors, showed that selling by SWFs resumed in the first quarter after modest net inflows of $382.3 million in the fourth quarter of 2016.

Peter Laurelli, global head of research at eVestment, said small inflows had broken the string of consecutive quarterly net redemptions, which began in the third quarter of 2014.

He added that the percentage of asset management products with outflows in the first quarter was the second highest in at least the last five years, at 70.3 percent. This is just shy of the 71.2 percent of products with outflows posted in the second quarter of 2016.

Some $16.9 billion was pulled from equity strategies, with heavy selling from U.S. equities. These lost $9.5 billion, whilst global equity strategies lost only $490.6 million, and global passive equity attracted $1.7 billion.

U.S. rallied to record levels in the wake of Donald Trump's election as U.S. president in November, encouraged by his promises to cut taxes and boost spending.

However, doubts about his ability to deliver on these promises have grown following problems getting a key healthcare reform bill passed.

This week the question of whether there was collusion between Trump's campaign team and Moscow has exploded into a crisis that may threaten the future of Trump's presidency. This triggered the biggest one-day fall in U.S. stocks since Sept. 9.

SWFs also withdrew $1.6 billion from fixed income strategies with the selling concentrated in U.S. bonds, which suffered $2.5 billion of outflows.

Laurelli said this was not a strike against U.S. credit, with U.S. corporate bonds attracting $1.5 billion, but rather a result of a $3.9 billion withdrawal from U.S. short-duration strategies.

Global fixed income strategies attracted around $1 billion of net inflows. Emerging market debt also pulled in $123 million, after three consecutive quarters of redemptions.

But emerging market equity mandates continued to suffer withdrawals, with some $2.1 billion redeemed in the first quarter.

(Reporting by Claire Milhench; Editing by Gareth Jones) ((claire.milhench@thomsonreuters.com; +44 0207 542 3571; Reuters Messaging: claire.milhench.thomsonreuters.com@reuters.net))