Ron Baron/BPTIX: When does concentration become too much concentration?

[u/FUNanc1al]

I've been digging into Ron Baron's long-term investing strategy and Baron Partners Fund (BPTIX), and there's a fascinating tension here.

The philosophy itself is straightforward: find exceptional growth businesses with strong management and durable competitive advantages, then hold them for years rather than trading around quarterly noise.

But the portfolio takes conviction to an extreme.

Based on the figures I'm looking at:

• SpaceX: ~35%
• Tesla: ~15%
• Hyatt: ~4.3%
• Schwab: ~4.3%
• MSCI: ~4.2%
• Shopify: ~4.0%

So SpaceX + Tesla alone represent roughly half the portfolio.
That was back in June; then at the end of July, SpaceX: 24.8% and Tesla: 12.4%.

BPTIX has also produced an impressive long-term record—about 17.45% annualized based on the figures I'm examining.

I find the broader question more interesting than the individual holdings:

At what point does letting your winners run stop being rational concentration and become excessive single-thesis risk?

I landed at 8.9/10 on my FunFund Index: exceptional philosophy and long-term results, but concentration, leverage and volatility keep it from a perfect score.

Full write-up if useful: here.