Jan 19 (Reuters) - BlackRock's spot bitcoin exchange-traded fund (ETF) hit $1 billion in assets in the first four days of trading, the first to clinch the milestone among a batch of newly launched ETFs tracking spot bitcoin prices, J.P.Morgan data showed.

The U.S. Securities and Exchange Commission (SEC) approved nearly a dozen ETFs tracking the world's largest cryptocurrency last week, after years of regulatory pushback.

Since the launch, BlackRock and Fidelity have pulled the lion's share of inflows as lower fees and name recognition appear to be key factors in drawing investors so far.

BlackRock's iShares Bitcoin ETF accumulated $1.07 billion in assets under management as of Jan. 17, followed by $874.6 million by Fidelity Wise Origin Bitcoin ETF, J.P.Morgan data showed.

The nine newly launched ETFs have drawn $2.90 billion in investment flows in the first four days of trading.

However, the Grayscale Bitcoin Trust, which was converted from a closed-end fund to an ETF, charges the steepest fee compared to the newly launched ETFs and has witnessed $1.62 billion in outflows in the first four days. (Reporting by Medha Singh in Bengaluru; Editing by Shilpi Majumdar)