According to the source, Bitcoin dominance has declined as altcoins rally, source: public social media post dated Sep 18, 2025. The source also states that institutions continue purchasing BTC through ETFs and adding BTC to corporate treasuries, source: public social media post dated Sep 18, 2025. For trading, this combination suggests potential relative strength in select altcoins while institutional demand may provide a support base for BTC, source: public social media post dated Sep 18, 2025.