The claim that S&P launched a new crypto index consisting of 15 cryptocurrencies and 35 crypto-related stocks is mostly true because multiple sources confirm the launch of a diversified crypto index by S&P, though exact component counts vary slightly across reports and some indexes track broader or different sets of assets.
S&P launches new crypto index consisting of 15 cryptocurrencies & 35 crypto-related stocks.

S&P launches cryptocurrency indexes, debuting with Bitcoin and Ether
Source: cointelegraph.com
Key Evidence
Coinpedia confirms a new S&P crypto index with 15 cryptocurrencies and 35 crypto stocks.
coinpedia.orgcoinpedia.orgS&P Launches New Crypto Index
Binance and MSN mention the Digital Markets 50 index offering diversified exposure to crypto assets including stocks.
binance.combinance.comS&P Launches Digital Markets 50 Index for Diversified Crypto Investment
msn.commsn.comS&P Launches New Crypto Index. The Digital Markets 50 Will Give Diversified...
Official S&P pages describe multiple cryptocurrency indexes but with varying asset counts.
spglobal.comspglobal.comS&P Dow Jones Indices Launches S&P Cryptocurrency Broad Digital Market Index -...
spglobal.comspglobal.comFAQ: S&P Cryptocurrency Index Series - Education+1 more
Reuters and Cointelegraph focus more on Bitcoin and Ethereum indexes without specifying stock components.
cointelegraph.comcointelegraph.comS&P launches cryptocurrency indexes, debuting with Bitcoin and Ether
reuters.comreuters.comS&P Dow Jones brings bitcoin, ethereum to Wall St with cryptocurrency indexes
What the Evidence Shows
Several sources confirm that S&P Dow Jones Indices has launched new cryptocurrency-related indexes aimed at providing diversified exposure to digital assets. Coinpedia explicitly states the launch of a new crypto index with 15 cryptocurrencies and 35 crypto stocks, aligning closely with the claim. Other sources, including Binance and MSN, mention the 'Digital Markets 50' index, which is described as offering diversified exposure to both cryptocurrencies and crypto-related stocks, though they do not always specify the exact number of components.coinpedia.orgcoinpedia.orgS&P Launches New Crypto Index
binance.combinance.comS&P Launches Digital Markets 50 Index for Diversified Crypto Investment+1 more
S&P's official pages describe broader cryptocurrency indexes such as the Cryptocurrency Broad Digital Market Index tracking over 240 coins, and other indexes focused on Bitcoin and Ethereum. Reuters and Cointelegraph highlight indexes focused on major cryptocurrencies but do not detail the combined inclusion of crypto-related stocks.cointelegraph.comcointelegraph.comS&P launches cryptocurrency indexes, debuting with Bitcoin and Ether
spglobal.comspglobal.comS&P Dow Jones Indices Launches S&P Cryptocurrency Broad Digital Market Index -...+3 more
The variation in reported numbers and index names suggests that while S&P has launched multiple crypto-related indexes, the specific composition of '15 cryptocurrencies and 35 crypto-related stocks' corresponds most directly to the Digital Markets 50 index referenced in some sources. However, some sources focus on other indexes with different scopes or component counts.
Overall, the core fact that S&P launched a new diversified crypto index including both cryptocurrencies and related stocks is well-supported, but exact details about component counts vary slightly depending on the specific index referenced.