Stock Market Midday, Oct. 6: S&P 500 Sets New High, Nuclear Stocks Surge

The S&P 500 closed at a record 7,840 on October 6, 2026, climbing 0.85% as falling oil prices eased inflation concerns.

Nuclear names led the tape after a Constellation Energy deal with Google. CEG sat at the center of the move, and the surge spread across the nuclear group. VST and TLN fit the same theme; the source names no specific moves for either, so treat any read-through as interpretation rather than confirmed price action.

Semiconductors added fuel. MRVL jumped more than 7% on strong guidance delivered at its investor day, a sharp single-session reaction that signals the market liked the forward outlook. AMD sits in the same semiconductor group, though the source gives no figure for it.

Memory was the weak spot. Stocks in that group declined on reports of Toshiba's market expansion plans. STX and WDC are the memory and storage names in this watchlist; the source quantifies no drop for either, but the direction was lower.

Interpretation: falling oil is the macro thread tying the index high together, since lower energy costs ease inflation worries and support risk appetite. The divergence between MRVL's gains and memory's slide shows money rotating by catalyst within semis, not buying the sector as one block.