The 10-year Treasury yield averaged 2.64 percent and the average investment grade cash spread has been 154 basis points above Treasurys, while the average high yield spread has been 462 basis points, said Adrian Miller, director of fixed income strategy at GMP Securities.
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The Fed's continued easing and the concerns about Washington's budget tussle put a bid in Treasurys that drove rates to a more attractive level for issuers, Miller said. There was pent-up demand from the summer months, normally slow but slower this year because of a jump in yields, he added. There was just $51 billion in investment grade deals in August.
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"It's all predicated on that bond market. With the 10-year closer to 3 percent, you had a lot of issuers sitting on the sidelines, uncertain which way to go," he said. "At 2.70 (percent), give or take, the math is different and the calculus very much different."
The market will resume its heavy focus on the Fed as soon as Congress resolves the continuing resolution to keep the government funded before Monday's midnight deadline, he said. And then there's the debt ceiling, which is expected to be hit in mid-October.
John Briggs, RBS head of cross asset strategy, said whether the trend of big issuance continues into October will depend in part on whether the stock market remains on an even keel.
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"Appetite for corporate credit can tend to decline during times of equity market volatility," he said. "Historically you get a post-summer, pre-October push no matter what rates are doing."
He said October can be slow because of a typically volatile stock market but then issuance picks up in November again before dying down before the holidays in December.
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Some of the issues Thursday were Ford Motor Credit and Credit Agricole, each with $1 billion offers. Wal-Mart offered $1.75 billion earlier in the week. There have been a good number of foreign issuers, including CNOOC and Korea Hydro Nuclear Power Co, issuing dollar-denominated bonds this week.
—By CNBC's Patti Domm. Follow here on Twitter @pattidomm.