[jcfrei]

The companies in the Nasdaq don't care much about the US defaulting: The cash (and cash equivalents in treasuries, etc.) don't make up a large part of their market valuation. If US defaults USD will tank and equity prices of public companies will soar (just like every other price including oil, gold, groceries, and probably also btc).

[hparadiz]

If that happens those companies will likely see an asset sell off as owners seek cash to buy basic commodities which will perpetuate a great depression. Sufficiently sized multinationals will relist themselves on different exchanges with other more stable currencies but the general panic will cause a downward spiral for most securities.