The S&P 500 SPX, +1.73% on Friday rose 1.7% to close at 4,280.15. A finish above 4,231 would mean the large-cap benchmark has recouped — or retraced — more than 50% of its decline since its Jan. 3 record high of 4,796.56. “Not since 1950 has there ever been a bear market rally that topped a 50% retracement and then made new cycle lows,” Jonathan Krinsky, chief market technician at BTIG, said in a note earlier this month. Stocks were broadly higher on Friday, with the S&P 500 notching its fourth straight weekly gain. The Dow Jones Industrial Average DJIA, +1.27% gained more than 420 points, or 1.3%, on Friday and the Nasdaq Composite COMP, +2.09% rose 2.1%. The S&P 500 tried to complete the correction in Thursday’s session, when it traded as high as 4,257.91 points, but gave up gains to close at 4,207.27 points. Krinsky, in a Thursday update, had noted that an intraday breach of the level doesn’t cut it, but cautioned that a close above 4,231 would still leave him cautious about the near-term outlook. “Since the reversal is based on a close, we would like to see a close above 4,231 to trigger this signal. Whether it happens or not, however, our tactical risk/reward looks poor here,” he wrote. What’s so special about a 50% refresh? Many technical analysts pay attention to what is known as the Fibonacci ratio, attributed to a 13th century Italian mathematician known as Leonardo “Fibonacci” of Pisa. It is based on a sequence of integers in which the sum of two adjacent numbers equals the next higher number (0,1,1,2,3,5,8,13, 21…). If one number in the sequence is divided by the next number, for example 8 divided by 13, the result is close to 0.618, a ratio called the Golden Mean because of its prevalence in nature in everything from seashells to ocean waves to proportions The human body . Back on Wall Street, technical analysts see key retracement targets for a rally from a major low to a major high at 38.2%, 50% and 61.8%, while retracements of 23.6% and 76.4% are considered secondary objectives. The push above the 50% retracement level during Thursday’s dip may have contributed to a round of selling, Jeff deGraaf, founder of Renaissance Macro Research, said in a note Friday. He noted that the renewal matched a 65-day high for the S&P 500, offering another bullish sign in a bear market as it represents the highest level in the last rolling quarter. A 65-day high is often seen as a default signal for commodity trading advisors, not only in the S&P 500 but also in the commodity, bond and currency markets. “This level coincidentally corresponded to the bear market’s 50% reversal level,” he wrote. “Essentially, it forced one group’s hand to cover shorts (CTAs) while simultaneously giving another group (Fibonacci followers) an excuse to sell” on Thursday. Krinsky, meanwhile, cautioned that previous 50% reversals in 1974, 2004 and 2009 all had decent volatility shortly after clearing that threshold. “Furthermore, as the market got excited about ‘peak inflation,’ we are now seeing a quiet resurgence in many commodities and bonds continue to weaken,” he wrote Thursday. Watch: Stock market euphoria meets bond pessimism as ‘strange week’ draws to a close