Despite their plans to enter the TV OS market shares in US audio Company Sonos surged 14.8% early this week mostly in response to news that Standard & Poor’s is adding the stock to its S&P 600 Small Cap Index.

They have since fallen back and were down over 5% overnight.

News of being added to an index can spark pre-emptive buying from investors looking to capitalize on impending institutional buying.

Any fund company that maintains an S&P 600-based fund must now buy shares of Sonos to reflect the index they’re trying to mirror.

Such a wave of buying, of course, can buoy a stock’s price that may not have otherwise been lifted due to performance of the business.

Sonos who are cranking up their direct sell market, has seen their stock fall over 9% during the last two quarters with the recent surge bolstering their poor six-month performance.

Nasdaq claimed that While an inclusion in an index is a victory of sorts for a young company in that it forces institutional interest in that organization, it’s not exactly a reason to buy it. And it’s certainly not a reason to buy it now.

They claim that Sonos’ future isn’t any brighter simply because it’s becoming part of the S&P 600.

They went on to claim that “If anything, the shares may be ripe for a little weakness headed into Wednesday’s transition, as too many speculators piled into it today on hopes that this is indeed the beginning of newfound bullishness. It isn’t.”