(Reuters) - Universal Music Group shed around $15 billion off its value on Thursday after the world's biggest music label reported lower-than-expected streaming and subscription revenue for the second quarter.

The shares fell 30% at one point and were down 26% by 1058 GMT, on track for their biggest one-day loss ever. The move has wiped off some 13.6 billion euros ($14.75 billion) from their value so far.

UMG's second-quarter subscription revenue growth slowed to 6.9% from 12.5% in the first quarter, missing the 11.1% estimate in company-compiled consensus cited by Barclays.

"The speed and quantum of the slowdown in subscription revenues caught the company and analysts by surprise," JPMorgan analysts said in a note.

The slowdown was largely due to the timing of price increases, Chief Digital Officer Michael Nash said during a call with analysts, referring to hikes by Apple and Amazon that were fully annualised in the second quarter.

"It's not that there's an increase in switching. It's really more about the competition for new subscribers," Nash said.

Streaming revenues were also below expectations at 343 million euros, versus a Visible Alpha consensus of 387 million euros.

The company, which represents Taylor Swift, BTS and Drake, blamed slowing growth at key advertising-based platform partners and shortfalls on certain platforms related to the timing of deal renewals.

"Investors bought UMG mostly for low-double-digit growth in paid streaming, in our view, the main basis for the rich valuation UMG trades at. If paid streaming growth stays lower, we see UMG multiples falling," Barclays analysts said in a research note.

They cut their rating on the stock to "equal weight" from "overweight", also flagging that streaming growth in the third quarter could be similar at about 7%.

Shares in UMG's shareholders, media group Vivendi and Bolloré, fell 9% and 10%, respectively.

($1 = 0.9217 euros)