After a significant but short-lived pickup a couple months ago, U.S. stock-market volatility has again receded to near historical lows. Market participants are questioning whether the decline is just a seasonal lull, or if it is indicative of a more lasting situation.

The CBOE Volatility Index (VIX) declined below 12 this week for the first time since April 12. The so-called fear gauge, a measure of expectations for market movements over the next 30 days, had touched 21 in June amid increasing speculation that the U.S. Federal Reserve and other global banks would start winding down stimulus programs.

To be sure, the VIX can be expected to be lower at this time of year given that the ensuing 30 days corresponds with summer vacations for many traders and investors. But a slow summer is hardly a lock; in 2011, the VIX soared from about 18 on July 22 to the mid-40s less than three weeks later, as U.S. government leaders reached an impasse on fiscal negotiations.

A low VIX can be seen as constructive in that it indicates there are no major near-term stumbling blocks or immediate, major broad market worries. But less volatility also means fewer profit opportunities for traders whose time horizons are shorter than buy-and-hold, and it also may be suggestive of a complacency that could prove problematic when issues manifest themselves.

Market participants and observers offered various viewpoints on twitter this week.

Jeff Kilburg (@TheKillir) tweeted “Fed balance sheet $3.5T VIX at 12 New Jobs per month avg under 200k Equities at All-time highs All is well, #CarryOn nothing to see here.”

Remarking on the recent run-up in the Standard & Poor’s 500 Index, Ryan Detrick (@RyanDetrick) said “Easier to see big swings when VIX is >35 vs <15.”

According to Helene Meisler (@HMeisler), “Put/call ratio at 73%. If you are bullish it had better be because the p/c ratio on the $VIX is sub 20% or this is bearish.”

According to a tweeter named Jag (@Jag92), “VIX has bottomed, but not SPX. just a matter of time now.”

Lastly, a tweeter with the handle Plato’s Bunker (@platosbunker) said “ get a longer term chart and u will see sometimes VIX around these levels for 2y/3y…just for perspective”