The FTSE 100 (FTSEINDICES: ^FTSE) ended last week up 1.3% to 92 points marking a second successive weekly gain. Janet Yellen was a success in her first public testimony as chair of the US Federal Reserve, and investors were cheered by her confirmation that the bank would continue to trim its bond buying programme. It would appear that US monetary policy is in capable hands.

It’s not all plain sailing for the world’s largest economy, however, as the recent jobs report revealed only 113,000 jobs were added to the economy in January. This was acknowledged by Yellen, albeit she still expressed confidence things were moving the right way, and her adherence to tapering should heed off volatility: no one wants a stock market bubble spurred on by cheap capital.

These were the shares that foundered last week:

Rolls Royce (LSE: RR.L – news)

Shares in Rolls Royce (LSE: RR) suffered their biggest single-day plunge for 13 years after the publication of its final results for the year. The aircraft engine maker forecast flat revenue and profit for the year ahead as lower demand for defence equipment cut into sales. Overall the firm reported a 41% drop in net profit.

A formal investigation is ongoing into Rolls Royce over concerns about bribery and corruption in its overseas markets. The allegations involve local companies that handle sales, distribution, repair and maintenance in countries where Rolls Royce doesn’t have enough people on the ground.

Tate & Lyle (LSE: TATE.L – news)

Tate & Lyle (LSE: TATE) last week cut its profit outlook due to weak sales in developed markets and a drop in price of the artificial sweetener sucralose. The FTSE 100 company, which provides sweeteners and ingredients to the food and drinks industry, reported that annual profits would be in line with the previous year’s £329m. Upon the news the share price fell by 15%.

The price of sucralose has been falling by around 5% a year, but there’s a current glut of unsold inventory from cheaper rivals in China that should speed up the decline, with Tate & Lyle estimating that sucralose prices will fall 15% in the current quarter.

TeleCity Group (LSE: TCY.L – news)

The data centre operator TeleCity (LSE: TCY) missed its guidance last week and the shares fell to a two year low of 633p.

Despite revenue growing 15% to £325m, this was below market expectations of £329m. Similarly profit grew from £76m to £88m but this was £9m below the figure expected.

Based on figures from TeleCity’s report, earnings per share of 37p will support a dividend per share of 7p. Therefore, TeleCity shares may trade on a P/E of 17 and offer a possible income of around 1%.

Finally, if you’re in the market for somewhat more dependable FTSE shares, then look no further than “The Fool’s Five Shares To Retire On”.

We’ve identified five companies in dominant market positions which we believe hold the key to your financial freedom. But don’t delay, as the report is only available for a limited time.

To reveal these ‘must own’ stocks for 2014 and beyond — just click here.

> Mark does not own shares in any company mentioned.